BU~LLETIN NO. 221JAUR,12 JANUARY, 1924 Life History and Control of the Mexican Bean Beetle By F. L. THOMAS In cooperation Bureau of Entomology, U. S. Department of Agriculture with AGRICULTURAL EXPERIMENT STATION of the ALABAMA POLYTECHNIC INSTITUTE AUBURN M. J. FUNCHESS, Acting Director CONTENTS PAGE FOREWORD-------------------------------------ACKNOWLEDGEMENTSINTR ODUC CTION_ -----------------------------__ 5 5 INTRODUCTION--------------------------------6 SYNONYMY------------------------------------------6 HISTORY IN ALABAMA _____-______------7 DISCOVERY OF THE INSECT PRELIMINARY Previous occurrence --------------------Manner of reaching Alabama-------------------8 -----------INVESTIGATIONS------------------------7 7 7 Biology and control work in 1920 ATTEMPTS - 8 PLANS TO PREVENT SPREAD -FOR FURTHER INVESTIGATION------------------10 9 DISTRIBUTION AND SPREAD------------------------11 FOOD PLANTS-------------------------------------14 CHARACTER AND EXTENT OF INJURY---------------15 ADULT INJURYLARVAL INJURY EXTENT OUTLOOK -------------------------------------------------OF INJURY-------------------------------- 15 16 17 FOR THE FUTURE-----------------------18 DESCRIPTION--------------------------------------19 EGGS-20 LARVA------------------20 --------------------------------------------PUPAADULT---------------------------------------------LIFE HISTORY AND DEVELOPMENT------------------22 SEASONAL HISTORY-22 NUMBER OF GENERATIONS-23 21 21. How to determine number of generations EMERGENCE OF BEETLES HIBERNATION-------------------------------------- --23 24 ------------------ 26 30 30 From artificial hibernation- __ From natural First Third Fourth hibernation---------------------.29 _____26 DEVELOPMENT--------------------------------------Egg laying by hibernated beetles--------------Second generation------------------------generation generation ---------------generation --------_------------- 31' 34 37 39 -__________ Summary of development --------------- 41 OVIPoSITIoN ----------------------------------------- 44 generations------------44 Records Relation to meteorological conditions----------- 49 FERTILITY--------------------------------------------- 51 of PROPORTION OF SEXES--------------------------------- Sex of overwintered DURATION OF beetles ---------__ 52 52 Sex of later maturing beetles--------------LIFE--------------------------------- 53 53 54 Effect of Starvation Mortality ------------------------------------ 5 -------------------------- PAGIT HABITS FLIGHT FEEDING HATCHING--------------------MOLTING AND PUPATION ---- 56 56 56 57 58 ADULT REPRODUCTION CHANGES IN 59 -----------------------------------HABITS 59 60 ---- NATURAL CONTROL ENEMIES CLIMATIC CONDITIONS 61 61 62 - - 63 63 INSECTS MISTAKEN FOR THE MEXICAN BEAN BEETLE 62 PREVENTIVE AND CONTROL MEASURES EXPERIMENTS IN 1921---------------------------63 Spraying and dusting ---- Fumigation experiments Other experiments EXPERIMENTS IN 1922 --- - 65 66 67 Plan and method of work Definitions --------------- ----- 67 - Insecticides used - --Experiments with bush beans Experiments with pole beans (P. vulgaris)Experiments with cowpeas -90 USE OF DUSTED BEANS AS FOOD - 68 68 71 82 Experiments with pole butterbeans (P. lunatus)- 86 --- - 90 SUMMARY AND RECOMMENDATIONSGENERAL SUMMARY OF EXPERIMENTAL PLATS ----SUMMARY OF INSECTICIDES -DUSTING APPARATUS -PREVENTIVE AND CONTROL MEASURES ----------CONTROL METHODS 91 91 92 94 95 BIBLIOGRAPHY -------------------------------- 96 -98 - FOREWORD During 1921 the Alabama Experiment Station and the Bureau of Entomology of the United States Departinent of Agriculture conducted research work on the Mexican bean beetle under a cooperative agreement -made the latter part of 1920. The writer was assigned to the work for the Experiment Station and Mr. J. E. Graf and Mr. Neale F. Howard came from the Division of Truck Crop Insect Investigations to take charge for the Bureau. At the end of June, 1922, the Experiment Station closed its share of the work and the data obtained have been prepared for earlier publication since the Bureau is continuing the work and will present a more exhaustive treatise on the subject in the near future. ACKNOWLEDGEMENTS The Department of Agronomy of this Station cooperated by supplying a collection of seed of leguminous plants and assisted in growing them. Dr. W. E. Hinds, Entomologist for the Alabama Experiment Station, has at all times willingly and gen-erously given valuable service and advice, contributing many notes which have been incorporated in the text of the bulletin. Practically all of the photographs were taken by him. The City of Birmingham cooperated in 1921 by donating the use of land for experimental work and Mr. °S. L. Brewster, farmer, cooperated in like manner. The Tennessee Coal, Iron and Railroad Co. did all in their power through their representative, Mr. J. D. Pope, to further the investigations in 1920. The Truck Growers in East Lake, Birmingham, were most generous in permitting their bean plantings to be used for experimental purposes. Mr. J. P. Bell, formerly of the Department of Entomology of this Station, greatly assisted by taking observations and carrying on much of the routine work of the project. Mr. W. P. Whitlock, student, ably assisted in the control work and in observing results of application of insecticides. To all of these and to many others thanks and acknowledgments are due and their services were invaluable in obtaining the results presented in the following pages. 6 INTRODUCTION The Mexican bean beetle, after being in the Southwestern United States for about 75 years, suddenly became transported to the Southeastern part of the United States where it has become not only firmly established, but a menace that already threatens the bean growing industry of the entire eastern half of this country. The insect refuses to be quarantined and its remarkable spread is bidding fair to break all records. SYNONYMY The first description of typical specimens of Epilachna corrupta was made by Mulsant in 1850 (1, p. 815) * and printed under No. 90. According to Coleopterists of the Federal Government, Bland in 1864 (2)* described the same species under the name E. maculiventris. Crotch in 1874 (3, p. 62) * places E. corrupta in synonymy recognizing E. varivestis Muls. instead, although the latter name was described as No. 91, following E. corrupta. Since 1874, all writers except Gorham have referred to this species as E. corrupta. Gorham in 1897 (8, pp. 242-243) * followed the lead of Crotch and not only placed E. corrupta in synonymy but also E. varipes Muls. and E. murina Muls., paying absolutely no attention to the law of priority, for of the four names E. varivestis was described last and E. varipes first by Mulsant in the original descriptions. According to Gorham that which constitutes the variety E. varipes is as follows: " . . and two subapical (spots) these latter sometimes united and forming an arcuate spot, this constituting the Var. varipes Muls." Considerable variation occurs in this species. Beyond this it is not wise to go until opportunity of examining the type specimens provides the means for deciding positively the specific name to apply to the species under consideration. "Epilachna corrupta is (therefore) used to avoid further confusion, although E. varipes Muls. was described first and is acknowledged by Crotch and Gorham to be the same species. * * (Chittenden. 24, p. 2) *In correspondence Dr. Chittenden has also written " . it was finally decided to use corrupta until some real reason for changing the name was known, although varipes to meseems to be the proper, name becauise first described." *Figures in parentheses refer to Bibliography, page 98. HISTORY IN ALABAMA DISCOVERY OF THE INSECT The presence of the Mexican bean beetle (Epilachna corrupta Muls.) first became known in Alabama, June 30, 1920, when specimens from Blocton and Birmingham were received at the Experiment Station. They were identified as Epilachna corrupta and the occurrence was reported to the Bureau of Entomology, July 8, 1920. The identification was confirmed by Dr. F. H. Chittenden who expressed the opinion that the presence of the beetle in Alabama was the result of a commercial "jump." PRELIMINARY INVESTIGATIONS As soon as possible a survey of the situation was made to determine the distribution of the insect and any other pertinent facts which would have a bearing upon it. This survey was only begun when beetles and larvae were found destroying cowpeas, a new food plant and one which is extremely important to the diversified agriculture of the South. The beetles were also observed feeding on soy beans. Four Counties, Jefferson, Shelby, St. Clair, and Etowah, were found to be wholly infested and nine others surrounding these to be partly infested. An early frost occurring the last of September put an end to further spread in 1920. Shortly after the frost a supplemental inspection was made by two federal men from the Bureau of Entomology. They spent nineteen man days looking for traces of the insect in seven counties in Alabama and one in Georgia, covering territory just north and east of the known infested area. The only finding was made at Jasper in Walker County, already known to be. partly infested. Previous Occurrence Another fact that developed in the course of the survey was that the longest and heaviest infestations occurred in mining communities. From what is considered reliable information, the first observation of the occurrence of the beetle in Alabama was "in the pole bean season (late summer) of 1918" at Blocton in the northern part of Bibb County. This observation was made by a miner who was also an expert gardener. He remembered seeing the characteristic "yellow bugs" at that time. The insect was noticed by a number of bean growers in Jefferson County in 1919, but not realizing the seriousness of the occurrence the pest was not reported until 1920. The majority of the growers in this county did not see the insect until the year 1920. Manner of Reaching Alabama Those mining communities which had the heaviest infestation are made up of families which raise a large share of their own food supply, especially vegetables and milk. The alfalfa hay fed to cows is obtained without exception from the commissary of the mining company. The origin of this hay was traced to sections of Colorado and New Mexico infested with the bean beetle, and it was learned also that one large mining company alone had received regularly direct from those sections for several years as many as ten carloads of alfalfa hay each month during early summer. The transportation of adult bean beetles in such hay shipments was rendered possible and more probable in 1918 because of the fact that the demand and war time prices for dried beans had greatly extended their culture in the West and for the first time brought the bean plantings into close proximity with extensive alfalfa-growing areas. In this way, or by what is known as a commercial "jump," the Mexican bean beetle is believed to have reached Alabama. Up to that time the species seems to have been restricted in its spread by surrounding desert and semiarid range country wherein the necessary food plants did not occur through long distances. Biology and Control Work in 1920 In the control investigations during late summer of 1920, preliminary experiments on snap beans with several proprietary insecticides as well as arsenate of lead, arsenate of calcium, Bordeaux mixture, sulphur, lime, and pyrethrum were productive of the following results: 1. Tobacco decoctions were not effective. 2. Sweetened preparations and bean decoctions did not prove attractive. 9 3. Calcium arsenate burned the plants. 4. Best control was obtained from use of Pyrethrum, calcium arsenate, and arsenate of lead. Mr. J. D. Pope, Supervisor of Gardening for the Tennessee Coal, Iron and Railroad Co., contributed the following notes of biologic interest: "COWPEA.-During August and September, 1920, only two examples of feeding on cowpea noticed. InInjury serious on pole and lima jury very slight. beans within 5 to 20 feet of cowpeas. FLOWERING BEANS.-August 30, 1920, observed characteristic injury on flowering beans (Dolichos sp.) KUDZU.-August 30 and subsequent dates in September, several specimens of Kudzu vine examined in neighborhoods where bean beetle was prevalent. No characteristic injury by bean beetle noted. On September 18, 1920 . . . confined 2 adults, 2 larvae, and 4 batches of eggs of bean ladybird on a portion of kudzu vine. The beetles were enclosed in a cheese cloth fastened tightly to the vine. Examination 26 days later showed feeding on the leaves of the plant and at least 12 adult beetles and 6 larvae resulting from the specimens confined. PEANUT.-September 22, confined 5 adults and 10 larvae to peanut plant growing in garden . . Septtember 29, 3 adults alive, no feeding noticed." During the early fall large numbers of beetles were Fobserved on late beans and more than 7,000 were collected for the hibernation cage. Because of the unus-ual abundance of the insects occurring late it was naturally believed that many would remain in the gardens for hibernation. Therefore, a winter clean-up campaign was inaugurated, the object of which was to destroy trash piles and shelter that would be most favorable to keeping beetles alive and to bury as many of the beetles as possible by early winter plowing in gardens and fields where infestation occurred. This campaign was well carried out and followed with advice to plant early the coming spring. ATTEMPTS TO PREVENT SPREAD In August, 1920, several pupae were found in a bunch of mustard greens offered for sale on the public market at Birmingham. And upon examination of a nursery where cowpeas were suffering from attack by the beetle, pupae were also found on the trunks of growing trees. Such occurrences as these at once suggested the possibility that infested products might be shipped 10 outside the area already infested by the insect and become sources of new infestations. These facts were placed before a meeting of state and government entomologists and quarantine officials held at Birmingham, September 21-23, 1920, to consider the situation created by the presence of this insect. It was determined that the situation was so critical that a joint attempt at eradication by the State and Federal Government was warranted, provided the insect was not found to be too firmly established or too widely distributed. At the same time a request was made of the Federal Horticultural Board to impose a federal quarantine upon the shipment of dangerous material from the infested areas. As a result of this meeting efforts were made to secure the passage of an appropriation bill by the State Legislature, then in special session, providing $250,000 for eradication of the Mexican bean beetle from the infested area in Alabama. This bill failed to get the necessary vote. The Alabama State Board of Horticulture placed a quarantine on the infested area November 20, 1920. Following a public hearing held in Washington, D. C., October 11, 1920, quarantine No. 50 was issued by the Secretary of Agriculture through the Federal Horticultural Board and became effective May 1, 1921. It soon became evident, however, that on account of its habits the Mexican bean beetle was not amenable to successful control by quarantine methods and on July 22, 1921, the Federal Quarantine was repealed. Shortly afterward the Alabama Quarantine was suspended. PLANS FOR FURTHER INVESTIGATION As the distribution of the beetle became apparent the importance of obtaining outside help for properly carrying on investigation of this new enemy was realized. Accordingly, Dr. W. E. Hinds, Entomologist for the Experiment Station, requested cooperation of officials of the Bureau of Entomology. Plans were made for cooperation to study and determine the biology, food plants, distribution in the United States, and methods of possible control, including native and imported parasites. 11 Quarters were established at Birmingham, Ala., in November, 1920, with Mr. J. E. Graf in charge of field control and Mr. Neale F. Howard in charge of research. The writer represented the Alabama Experiment Station and is responsible for the results presented in this bulletin. DISTRIBUTION AND SPREAD Epilachna corrupta Muls. is a native North American insect having been known in the United States since 1864 and as a serious pest in Colorado as early as 1883. Until the year 1920 only four States, Arizona, New Mexico, Colorado, and Texas, in addition to Mexico and Guatemala were known to be infested. That year in early summer it was found in Alabama acquiring new habits and appearing far more serious as a pest than in the Southwest where it was previously known. Although its presence in Alabama was not known until 1920 a few growers in Bibb and Jefferson Counties had experience with this insect in 1919, and it is now believed that the infestation did not extend beyond these two counties at that time. At the end of 1920 beetles were found in 13 counties, of which 4 were wholly and 9 partly infested, covering an area of approximately 4500 square miles. WHOLLY INFESTED 1920 PARTLY INFESTED Etowah Jefferson Shelby St. Clair Bibb Blount Calhoun Cherokee Chilton De Kalb Talladega Tuscaloosa Walker Scouting to determine the extent and rapidity of spread by the insect in 1921 began in April under the direction of J. E. Graf of the Bureau of Entomology By June 4, when the first generation adults were beginning to mature, 3 counties had been added to the list of 13 in Alabama; 8 were found infested in Georgia, (6 of these bordered upon Alabama) and in Tennessee the beetles were found in 2 counties near Chattanooga. The number of infested counties at this time was double the number known to be infested in 1920. By June 26, Mr. Graf reported the total area infested as 23,505 square miles of which 13,178 square miles~ 12 were in Alabama. From June 4 to 26 there were added 8 counties in Alabama, 12 in Georgia, and 12 in nessee. In the next two months, June 26-August 27, the infested area was increased by 45 counties extending into 6 states and comprising 38,959 square miles of which 18,827 were in Alabama. For the remainder of- the year only 8 new counties were reported. A summary of Mr. Graf's weekly reports appears below in brief tabulated form : Ten- 1921, TABLE ___~ 11 OOCa I.-The _1 _ -~ _P number infested area in the South, 1921 \~/ TT~PC~ of counties and States added to the -- af'a Date rif o'14 rrn nc "t z a a 1920 December -____ 1921 June 4-----------(3 weeks) June 26 -F 13 (4500) *I Of j8j1 I H I 001OfOf01 0--- I I I 4,500 August (2 months) -27 --- - - - 8 3 34 Of OOff 13f - 8(13178)*112112I S1 I I I October Total ----- 22 _ _ _ _ _ _ 9(18827) *f121181 31 21 i1 1 1 41 21~ 01111 1361341 I II I Of OfOf I 32.1 23,505 I 45f 38,959 31 21 2.1 981 --- 81--- *Figures in parenthesis denote total area infested in Alabama. The Counties in Alabama were as follows: WHOLLY INFESTE B Bibb Blount ,Calhoun Chilton Clay Cherokee Cullman DeKalbEtowah Fayette Cleburne -Coosa Jackson Jefferson Tuscaloosa Lawrence Walker Winston Madison 1921 Marshall Morgan St. Clair Shelby Talladega , Colbert Dallas Franklin Hale Lauderdale PARTLY INFESTED Limestone Marion Pickens Randolph Tallapoosa At the end of 1922 Mr. N. F. Howard of the Bureau ~of -Entomology reported as follows : the only spread southward in Alabama occurred in Autauga County. It is worthy of note that the- insect was not present where scouting was done in several localities where' it was found in 1921; notably in Tallapoosa, Coosa, Dallas, and Bibb Counties." ~~ 13 CA BfN How ,RA V. pEL dAY SxEL L/CKIN MUSKGV v BE GREE WAR /P GL/N TIP RqM ? MIA CNf M 0 F O M r MONO G WE RE 0 A1R PE Z MORG MA p PRE Q v CL AR yfR p0 B00 ~AM NE WAY /y0N /0 MrRSN Ty 0 HAR TA NAN PR E y 110CK PV BRR rU MEN At0R ATH 00 EDG PAR '0117 loe SHE RU5 fRAN BUTL WA NOR A C G Q NAM/L CL 'ti H/G ROSS I/VT SIG MA 00 JAS R/TG LBW Qy$1 RAN O R. CLAR v 0 BR /p/KE ~ BRAX B P y RIP 8R OR S TOT G sa As GRr:E 1AC[C ~e -wtY' Li! LAY LAW LA t 0 OA WA5 ' ; 490191 CARE i LA a PL' ' f(A VA vley / CA !t itR C rR NEN °1sc N C /LE LING FAME GREENER OR oc -c BOpN IV PV DUB CRA P o fR BD pyti'0 ELL LAW JEFF ND SHEL Ay CtF Cal ME MOR ~OH N cL 0 PAL SUMMON AEG WYO G¢ W GIBS AXI e 40 PE E PO MA WO MA PLO p/KE OO Al NE A ME EST LE BREA Mc00 MCIIGIP ? RO G UN/ NEN DAV BRE LAN M R/ 80 L/ RO ~A OW KN UC T E L /o/!L O 0I F 0/ .. / fL HA WEB OHIO CRAYS AD 11 LAS LAU CLA LE LET LA yy/$E U GRRR pAT CR/T HOP Burt I MUL! CA BAR /HE CU RU WAY Q. K HIT BAR WASHwage ! Al R A0 SURR STO N CL/ LYO CHRI 0 LOG S , Al Ir A ''IOM CLA/B NA HAw AR W FO MA TRIG PI CLAY CAL STE two S u tso JAC DYE F 6 fF 0 G CA L ( E z DAV D yq SMi f HENR u ? 0,4V,, P WILS MAO A ROWA CK I D S SUNG C CA S OU RR HU j jq HAY R(/7N rv/Lt /A MEC CL NPOt UN10 CPA HEN V /° RI MA NE1) MA' SPAR A YORK N t_ ES 0 La r NARO ty LAW G/[ F IN ANDS RU w, LCO T/ A DEL A GREF. 5A1RAH PRE CO LEONG O E 'T F OGLE L1 EDO CA WAL p v COL g1 KEN OR R I-A AM JAS PU NANC WA, !C BUR BARN RAM SPA JEf U A MER I n MON LION BAL. / W/1 K VAS/ JE SLRE LAMP AI 0 U HN MRN CPA LA CIA BULL _ NARR TALB A AUHE IF iP P C-RE HAL Yg P 5UM ACO RUSS PERK 4 7PrD) U EL N10 A MAC L TO ' " r+A C ' A D00[ DOD 7 T N DALLA LpGO ,y,4RF SULL0 5T1W E SUM7 GRI WILL ELFAJ 0 Pp1,! RT L!BE - QACO /R E ruR HILL WAYN M /N , recL Its. f ested. f 71 71 17 71 1,920 192 V922 19 2 OUGNwoR T/F' GOffE PJER 6LYN K ITC COLA BERR/ WAR CAMDE LOw CL/NC KAAG NASSA GR BR0 ECH 2 3 Q DUVAL o I'so of ed InfeSt ZOn ,21 N EO J svWA s o R CLA Map showing spread of the Mexican Bean Beetle in S. E. Unite- States. After Bureau of Entomology, U. S. Depart ment of Agriculture, 14 The greatest spread for the year was recorded in IKentucky where the infestation extended 110 miles be-yond the nearest point in 1921 and was found only 30 miles from the Ohio River and Indiana. The progress of the infestation in the South by the Iexican bean beetle is shown by the map on page 13. A glance at this map is sufficient to see that there has been a decided tendency to spread in a northerly and easterly direction at a very alarming rate. An examination of the meteorological records shows that during spring and summer when the adults of E. corrupta are in flight, the prevailing winds are from the south and :southwest and this may be the decisive factor in influencing the direction of the spread. FOOD PLANTS The foliage of garden and field beans constitutes the -chief food of adults and larvae of the Mexican bean beetle. The beans commonly known as string, snap, pole, kidney, cornfield, corn hill, bunch, navy, and shell -beans (Phaseolus vulgaris) are preferred, but lima or butter beans (Phaseolus lunatus) are also attacked and destroyed. Young beans, especially of late plantings, rare quickly injured. Upon the destruction of beans, and in badly infested areas, the insect will attack other leguminous crops, namely, cowpeas and soybeans. The writer has observed instances of complete destruction of cowpeas, but up to the present time such observations have oc'curred only where cowpeas were in the immediate vicinity or adjacent to destroyed bean plantings. It is rare that soy beans are seriously attacked. During the season of 1921, 38 leguminous plants, including several varieties, were planted in a heavily infested area for observation of the feeding habits of the insect and the amount of injury produced. The folplants are those on which complete development from egg to adult was found to take place and are arranged with regard to their preference by the beetle. lowing 15 HOSTS UPON WHICH COMPLETE DEVELOPMENT OCCURS Common Name Scientific Name 1. Beans (string, snap, etc.) ------------ Phaseolus vulgaris 2. Beans (lima, butterbeans) ------------Phaseolus lunatus 3.. Beggarweed---------------------------- Meibmia sp. 4. Cowpea-------------------------------Vigna sinensis 5. Hyacinth bean------------------------Dolichos lablab 6. Soy beans---------------------------Glycine hispida 7. Adsuki bean--------------------- Phaseolus angulatus 8. Similar to hemp--------------------Crotolaria juncea 9. *Alfajfa-----------------------------Medicago sativa 10. ---------------------- Pueraria Thunbergiana *Reared in confinement. **Record from J. D. Pope, T. C. I. and RR. Co. Sweet Clover (Melilotus) is included by N. F. Howard in a similar list (28, P. 23), but the writer was unsuccessful in getting complete development on this plant although larvae in all the different stages, as well as adults, fed slightly when confined with it. Velvet beans, crimson clover, yellow clover, peanuts, lespedeza, hairy vetch, garden peas, horse beans (Vicia), coffee weed, Urd bean, Mung bean, and Jack bean were practically immune from injury at the time they were tested. However, cases of accidental feeding have been found upon Jack bean, corn, and velvet beans, resulting from intermingling of these with host plants. Velvet beans and okra have been attacked by third and fourth stage larvae following the destruction of the host plants in adjacent rows. Leaves of white clover (Trif olicum repens) were eaten considerably by adults in confinement and in one case even carpet grass was eaten by beetles when no other food was present. CHARACTER AND EXTENT OF INJURY ADULT INJURY Both the adult and larval stages of this insect feed chiefly on the leaves of beans which soon become skeletonized and drop off. The adults when feeding cut irregular holes through the leaving portions the upper epidermis, the larger veins, and a network of tissue which resembles veins. network of leaf tissue may appear within the freshly made holes and on the lower surface of leaves where this insect has been at work. The vein-like network is very char- of leaf, This 1(i flctcIis[i( of f(4(IIIin II\ this sj)4L(1s. Althoughtit IIW (14the largo. Im(Vs as a4 14 stlt wor S((4i n ( si 14)4U s I 1441 ()ol also 4411 1)4fo n ( 1411551IIils. lords, .i c((Iinlg on1 thll l 1 \"c(I 14 fi4' hri 4 1 11ir !411w;I5. im n t cd '5. 'Flic~~~~~~~~~~~ V.I J H oiochr hl-'5~yvrcosftd~sn cothii of fillcd aiuhs\ licv raI tI' oiii to4( coniliii 44(ic114 in sril t 111412 14o14d. t Ih I( l;41\I thit l441 ly~('rs vciiis andl( so cl Ii Ict ( iIsti iicf\\ oilso (-al'21 tissue \\ hichIi s \Xliii-like The ~ii I oil th1iIs in1154(. 141 1114 X of wh Iitishi ai4;ls rani mI fhit (I'44XX tit h44 5(411 on4 1111 ilhpl)4I surfl1 is eci('&hsed s ut Wh4.( XX ithout anl 114ev dry\ l) Tl114 \1'~ ca1 1 11 I)L'4'll4 i I-, cit h st i 11rIi(411 1)c51 OI1 I ll 4\\ '444 Iiur I's I c' cO s 14 >11 tcs. ill ll)' l uit(l 144 Ills [ll c44 Inly jiIE' 414 jtIl! WI 441 1114tI4't1 i 4''' 4's11144 4)1 juitI -1)(i~ v t111 lcn ll d(v l 11 lip ~uv ul Ic4(',1 1 1 f h 11 'l u c.44111 I i))(Xthe (Il rc5 1(44)1 It) [('11(I L I' , 'I, he)1 nuII nid he>zcofllc1)an ;atac< 4,1cl II ic- N 4'I'N 111I4's11)tli)11 I IL~'~14141 11 N4)11 51ii2111 o114 )1-' iI)11111411 c1414 it141)l 41 41' 4)14 1 tt,'(vIi 4'11 Iva 44truck- cr i NN _) Ii theiii Fr t tts t "l l''''~ ll i'l . s O c aI')' ~a r J c (i c I ' I I)41) I'445 ~ 41 NNlt iiitt'sV 111' ~ ~ 11114 ~ " ji~j'j 1.l 1 18 66 days after coming up. In a little over a month the peas were 100 percent infested and injury had become serious. In this case the cowpeas were adjacent to beans which were destroyed by the bean beetle. Cowpeas are not usually injured except where near bean plantings thus destroyed. Three varieties of soy beans (Virginia, Tarheel, and Hollybrook) were planted in the same half acre and at the same time as several varieties of beans. The beans were destroyed by the beetles. The Virginia soy bean was the first of the three to mature and the Tarheel was second. Both dropped their foliage without noticeable injury. The Hollybrook soy bean, being the last to mature, may have had a slightly greater amount of feeding injury, but the average farmer never would have suspected the presence of an injurious insect from the general appearance and development of any of the soy bean varieties. The percentage of loss for beans and cowpeas ranges from nothing to a complete crop failure, averaging around 70 percent for beans and a very small percent for cowpeas. It is rare that soy beans are injured enough to attract attention. OUTLOOK FOR THE FUTURE The Mexican bean beetle is a pest of major importance. But the fact that it practically failed to spread south and west in Alabama in 1922 has given encouragement to the thought that possibly, after all, this insect may not prove to be as serious to southern agriculture, at least in the Gulf States, as was supposed three years ago when its presence was discovered. Forecasts regarding injury by this pest must be based on its accomplishments in the past. In the vicinity of Birmingham the destruction of beans was greatest in the fall of 1920; it was noticeably less in the fall of 1921, and in 1922 late beans suffered very little The isolated infestation at Thomasville, damage. Georgia, is barely holding its own after two years. Personal observations supplemented by diligent inquiries have led to the belief that cowpeas and soy beans have not been severely injured except in extenuating circumstances. The following average yields of cowpeas in 21 of the heaviest infested counties are compared with the aver- 19 age for the entire State for the years 1919-1922, inclusive. The figures are taken from the latest and revised estimate of F. W. Gist, Statistician, and are the official records of the crop reporting service. TABLE II Yield per Acre of Cowpeas District I 1919 bu. 6 1920 bu. 1921 bu. 9 1922 bu. 7 Tennessee Valley 6 Counties Mineral 9 Counties Northeast I10 10 1 6 6 6 5.6 I 9 9 9 8.5 8.3 6.8 7.54 6 Counties I Average, 21 Counties (Infested area) Average, Entire State__ 1 10 10 9.7 7.31 In its new location the beetle is in a different environment and under different climatic conditions than it has normally been accustomed, heretofore. It is impossible at this time to foretell the injury that may take place under these new conditions. J. E. Graf, of the Bureau of Entomology, stated in a paper read at a meeting in Memphis of the Cotton States Entomologists that the presence or absence of suitable hibernating quarters will have a greater influence on the existence of the Mexican bean beetle than any temperatures that may be involved. He reported that the pest has been found in Colorado at an altitude exceeding 8000 feet where the temperature went 30 degrees F. below zero. No native enemies have been discovered that give promise of checking the multiplication of the bean beetle and practically all who would grow beans in the infested area must turn to methods of artificial control at present. DESCRIPTION In at least three stages, larva, pupa, and adult, the insect is conspicuous in appearance and easily distinguished from all other insects. LA((s 'Tilc \\i It cogs oe Itlin ou (lull il i i' ;Ill ;)[l( ut k iI (tIs i(I. 'InIl !uIuu;ltln 1 ' liii I ni "Mlle firs! illsh)r hin t is ;dmut 1.5 01111. 1011;), (rile greenish-y('11 v in color, ;111(1 its hold ,v i, ;u"lllcd wilh shines. III( I; 1w is Imvc four illst;u"s, 111nltin" (lire(, lilacs Ilrcvi(llls to lll(, llull;lli(lll molt. 'Mlle (Ic (,lollin .111(1 11lulurc i:ll v'lc ;Ire yellmv. \\ilh G roes 0f shines \\Ilic"il be(((nt( stro11gly Illnnrllc(I un(I Illucl< ;lt Ill(, tills, 1110 (kIl-k C(d(X IWi11 i (luC to c001 WIlllu'r;I;urc, ;111(; is 111orc P1,01nincnl in "((ring ;llld fall. W ilcn m cr IrIll, gro\\ 11Ills I;ll ;1 211111(, lrs to 11e "Iltunllll:Ic"ke(I". Ill(' lo11gc,.t ,(lines ;md Illc thick(,,( llorlio11 of tile Ilo(lY Ileilig ill lllc 1ui(l(I1e. 'Mlle ;lhdO11lcl, in ;111 illsl;u's tull(,rs l) Ill(, 2ul;ll scgmci 1 v\Ilic"I1 is llro(lurc(I to hwill n suc-kcrlikc ;Illlrtrnhls by Mlich the lur\;t is ;1i(Ic(I in rli11gi0g to tllc k-A, ;t0(I by \v Ilich it f;Islc11s itscil, llre ions to ).I 11lolti11"i. ThC I'ourlll illSkl1" llll'vn is ..- 111111. 10 11c;lrl\L;Ir\uc u"c 1 cm. ill Icngtll u11(I ;lhmll 11;111' rns illustrated 011 1r,1gc 22. Thlpitt i i s ligt tcadll. c L .Na zoP I no o\ iit Ica is a 1(ana) is p)1((Ply I)Pi crtsill. w ich'is i [a~a svihe whL ~i i j s Iits t. Ii ; it tip I'tliittliii' ~t pu ii It ' 5 ( ( e li kefi~p iilcr Ant n inco h sjits. I~ist j~o5 Nliv 10 ist. -lik st ae.l5(t Wh'Itt (ile Pic iIi ii('(l LnN s tlt PIpiN 1)c ot other( p war liein fi pulri iiis to iro5 i 0(1 50111 N\~ t'usct: iii5 tiiig .i i oft atitil lt groing ne)0( tItis tra.ther 'F 'lx c adult.is liigl robust xnii-ovoiid Vctl \v ith . inifiili inci. to u on-.(hh ofa 21 i andpi s1 ic shc NNilig ciN es flt:'(lcliticalo br dcsci'ip io fi yn zc ~tfiSfownih m ih 1)11 ii: I ;Id iill pric I ( Ii i itl~ u I I I s I-a l Iulc. liiic rms. i n dcI me i trtt\\ti FMtliit IcssI i tt Ililt I in ;,l Ir i I c tBiifsi HCc mciddclcc, uscii l \~ iii Ii'i i IIsca v ii 121it1 II a III II r (iit I 1 11kr11. ri flit 11 t li i 11 1 ii i 2 ('11 IIiid21111)111 c urfac l nc lru s il lms 23 April 6*. Emergence from hibernation continued until after the middle of May. After feeding 8 to 15 days the beetles lay eggs. The eggs hatch in 15 days in early spring, the time shortening to 6 days in summer. In 1921, the first eggs found hatching in the field were discovered April 7. Larval development usually requires 14 to 19 days, except in the case of the earliest of the first generation larvae which may require as long as 36 days. The pupal stage lasts 5 to 18 days, the longer time occurring in the fall. Total development from egg deposition to adult transformation requires, on an average, 30 days, the period ranging from 25 days in summer to 56 days in early spring. The maximum injury by this pest usually occurs in July and August; fall beans, as a rule, having little chance to produce a crop. NUMBER OF GENERATIONS In addition to the over-wintering adults the Mexican bean beetle has two complete generations and a partial third. in the insectary in 1921 and a single fifth generation adult developed after the occurrence of a killing frost, these records must be considered exceptional because thie beetles are descendants of the first adultsmaturing Although many fourth generation beetles matured from the first eggs laid by the earliest emerging beetles in the spring of 1921. In other words the records are the result of "first selections." On the other hand it is equally true, and likewise exceptional, that a few beetles of the first generation entered hibernation in the fall of 1921. How to Determine Number of Generations: To determine, theoretically, the average number of generations and the crest of each for a long-lived insect laying a large number of eggs and having several overlapping broods, the following "rules" were used. 1. The infestation for over-wintered adults begins with the first appearance in the field and .ends with the death of the last hibernated beetle. 2. Determine the date when one-half of the overwintered beetles have emerged and allow an average *Record by N. F. Howard. I Oi I l cii sl citI Illi i'\~i ii I lion '' 4 ii I'm ' t'i'r-i tt c vvlcn Ili l lit 1. s I~a c tcc Th IIi l tv lilt l ;Itl I C iii S - ~ ~~ ~ ~ fu'i ~ ~ lkstto ~ 'ic"tonu ~ Firs uls iirs 1$in of~~g>crlin ~ 4(4liii. 1u lct~ isn an occur n vv lcn tlcr;1 fclilc whic llt gI II\tl ISt w Ii in Ii X)1. t'( iiL4I 1111,.:ItN v is It' Nn l~lc ' l2 (lc lu') Il 'ill I h~lio1 titIS( (IcllCA I [iiiI ic . "\iiA- t I)ci i'I i''. I ( i1 in 1it _______________lt\ lt' t01t'\ t' '(1 ()l 190 - 1 'rdn n adults.~~~~~~~ . li Iivi I (tm vnile Ii ui l"v nc t'- 12 It lc i ad ls.iul d Il Ilih li it tiht il XXaIing llats i t I iccc 'l I 1lilt 'Iitt I t c10 hit~iIti. 26 'but usually considerable moisture is present. As hibernating material dries out, the beetles seek a moist location and go deeper under the leaves. On warm days they become active. A few beetles have been found hibernating one mile from the nearest bean field, 25 individuals three-fourths of a mile from the nearest field and large numbers one-fourth and threeeighths of a mile from the nearest fields. The majority of those observed, however, were within onefourth of a mile of bean fields which had been destroyed." resting on the ground. . . The beetles ordinarily have been observed under good drainage conditions In addition to pine needles and oak leaves a hollow log was found in one instance to be sheltering many of the adults. Apparently the beetles exhibit a tendency to be gregarious in hibernation, a characteristic habit that exists among related species of the family Coccinellidae. In 1921, five generations went into hibernation in the insectary. The number of beetles in each generationwas as follows: 1st Gen. 6 2nd Gen. 35 3rd Gen. 84 4th Gen. 69 5th Gen. 1 Total 195 Howard (31, p. 270) has found that 5.37 percent of the 2nd generation, 55.17 percent of the 3rd generation, and 90.88 percent of the 4th generation enter hibernation. EMERGENCE OF BEETLES From Artificial Hibernation In October, 1920, approximately 7700 beetles were collected and placed in five compartments of a hibernation cage built for the purpose of studying emergence of beetles from various types of hibernating material. The cage was 8' x 12' x 41/2' and the top and four sides were covered with 16 mesh screen wire. The first beetle found in the field in 1921 was on March 22, and on the same date an egg mass was found.* Ten days later the removal from the cage of beetles found active on the wire began and the results are considered The materials as an indication of the emergence. placed in the several compartments, the number of beetles present, the date and number removed all appear in the following table. *Records of N. F. Howard. 27 TABLE III Relationship of Hibernating Material and Emergence of Beetles, 1921 Materials . r+ a a° j cu * cy + 0°~ Q - oQ0 - No. beetles in cage on Oct. 23, - 1920.- 1600 1600 O 1600 j M 1600 ;_42 950 * 7350 Emergence April 1 5_ 98 69 3 13--- 7-__ 9 __ . -____ -___- 21 49 1 1 0 0 0 0 0 0 0 0 0 0 0 0' 0 21 9 7 5 0 11 10 120 79, 28 54 21. 23 28 21 29 ___ May 10 ____ 19.. June 14 80 0 0 3 0 0 0 0 0 1 8 8 4 2 29 25 94 3 24 14 28 8 4 1 3 7 Totals-------425l 5 0 4 1881522 Percentage 26.5J .3 0 .25 I 9.3 7.1 * Remainder after 350 were removed from 1300. ____ 0 0 0 I 0 1 0 0 0 0 3 32 18 33 On March 161 active beetles were counted in the hibernation cage. They were not removed. The first collection on April 1st, netted the largest number because of the accumulated emergence up to that date. All collections 19, 7:30 A.M. were made at the same time of day, A source of error occurs in the number' removed from compartment No. 5 where there was nothing but bare ground. Entrance into compartment No. 1 was through compartment No. 5. A wooden strip which had to be removed when entrance to No. 1 was made was not always fitted back as tightly as possible and on these occasions beetles were found in cracks which would permit passage from compartment No. 1 to compartment No. 5 or vice-versa. This did not occur until after removal of beetles began. 28 Of the 1600 beetles placed in compartment No. 1, in which there were old shingles, parts of crates, and loose wood, 26.5 percent were removed. Less than one-fourth of 1 percent of 4800 beetles came through the winter in three sections of the cage containing corn stalks, heavy grass, leaves, weeds, etc., while 9 percent of 950 were removed from compartment No. 5 where nothing in the form of shelter occurred. Allowing for the greatest possible margin of error the survival in compartment No. 1 was not more than 493 beetles or 30.8 percent. The reason for the low survival in the other compartments of the cage is not clear unless it be that the corn stalks, heavy grass, weeds, etc., which were cut and lying on the ground, became wet and heavy as a result of the numerous winter rains causing the beetles to succumb to the constant dampness. The winter of 1920-21 was slightly more severe than that of 1921-22 but it is reasonable to suppose that the emergence was about the same. Only 3.5 percent of approximately 7000 beetles placed in a hibernation cage in the fall of 1921 survived, but in this case the sheltering material was undoubtedly insufficient. It consisted of grass, weeds, loose bark, rotten wood, and a few boards. On November 3, 1921, at the close of the season's work on life history, 195 pedigreed beetles were carefully provided with hibernating material consisting of rotten wood, paper, and light trash and placed under shelter where they would not be disturbed during the winter. This location and condition proved too dry for the beetles, not one surviving. The hibernating insects were distantly removed from the Auburn headquarters, preventing observation until too late to correct the conditions. Of the 522 beetles that passed the winter of 1920-21 in artificial hibernation 54 percent emerged by April 10 and 88 percent emerged by May 1. The following year, 1921-22, 69 percent of 251 beetles emerged from artificial hibernation by April 13, and 100 percent by May 1. The cage experiments in artificial hibernation indicated that emergence was practically completed by the first to the middle of May, depending on the degree of shelter which the warm spring weather must penetrate. In 1921-22, with less protection in the cage, emergence was completed earlier. 29 From Natural Hibernation Data upon emergence of the beetles from naturar hibernation were obtained by keeping a close watch and recording the increase in adult infestation on 21 acres of beans which were located in an area one-half mile square with pine and oak woods adjacent on two sides and more distantly located on a third side. This area is used largely for growing of truck crops, and beans have been a main source of income. A heavy infestation of bean beetles was present in the fall of 1921. In the spring of 1922 the first record of the occurrence of an adult on beans in the field was made on April 6 by N. F. Howard. On April 13 the maximum for any plat was 1 beetle to 100 hills of beans or a 1 percent infestation. This infestation increased very rapidly, as follows: 4/13 4/16 4/25 5/1 5/9 5/12 (4 plats.) 5/16 1% 4% 16% 20% 29% (40% 44% 50% 56%) 68% The first time that a 100 percent infestation was recorded was on May 11. These records were not carried beyond May 16 for as the infestation approximated a high percentage the beetles became restless and would occassionally fly away in search of fresh food. Although the duration of the emergence period. was not obtained a heavy emergence about May 10 is indicated by the rapid increase in the adult infestation of bean plantings. These results tend to show that emergence from natural hibernation is slower than emergence from artificial hibernation. This is readily understood when it is kown that the beetle prefers to hibernate in accumulations of leaves, usually in the edges of woodlands, in locations that are less accessible to the warmth of the sun's rays than the hibernation cages constructed in the open. - AA St U Iic eIost5 lolhli. e h\istorl isitu~ic sct ( USlin wilS th ei Ieli ,uitclrs a ultso m 1 )aihin iut! 1921( Cllinii' tin ial~l I'e'the .\scltolls \e. ot chccst bhicli Itillhullsf'I\ ilt IovcreI il 110 f the ca(Ic toli' c(i h ',s f tll( of~t cill ulIcnia (iul) tes 1 (1 the tou t1ioitii plat (I 31 TABLE IV Egg Records of Hibernated Beetles, 1921 ~~JJ Beetle ~O 4/15 rs n1 b ~r -48 35 33 13 46 1 ----5 6 -----11 12 7/6 6/13 - 26 16 7 ------- 4/14 4/19 5/18 4/15 5/23 6/18 9---------4/26 ------------- 5/30 5/19 7/16 21---------4/20 24---------4/19 4/22 25 ------5/13 38 -----5/27 -42 ------6/15 j '64 7/31 6/17 5/19 6/9 6/9 16 5 4 24 20 17 8 16 1344 789 883 274 81 1332 1152 956 466 6/2 5/19 82 58 5/22 5/24 5/9 6/1 6 60 92 12 23 69 58 27 8/19 5/26 5/1 5/19 27 36 11 7/29 17 6/221 3 828 657 935 1 125 12 27 13 30 7 5/26 7/7 Totals -- I Averages i 1 183 1 9822 I 6/1813I7 13401628 1 41I63 14.01 755.5I26.1148.3 23 Earliest date on which hibernated beetles laid Latest date on which hibernated beetles laid eggs - - - July 31 Days Egg laying period for one female: Average----------------------------------48.3 Maximum -------------------------------- 92 Minimum----------------------------------7 Number of egg groups laid by one female : 14.0 Average ---------------------------------Maximum eggs-March Minimum ---------------------------------- 3 Number of eggs deposited by one -------------------------------- 26 Number Average---------------------------------755.5 Maximum-------------------------------1344 Minimum -------------------------------- 81 of days required to lay '/2 female: her eggs ----- - -26.1 days First Generation The incubation period, time required for larval development and the pupal period are tabulated in the three parts of Table V. According to the weighted average time required in the egg, larval, the total period necessary for a first generation beetle to develop from deposition of egg to transformation of adult would average about 33 days. -and pupal stages 32 TABLE V Development of First Generation EGGS Number of Records 2 10 6 I _ _ -_ Incubation Period Egg Days 14 28 13 130 12 ---------------- 72 11 ---------------- 33 --3 1 10-----------------9---------------10 8 9 72 8-----------112 14 -----27 7 189 52 -------------------6 312 12------------------ 5*----------60 135 1018 _ -__ _ __--- 1 -- - - - - - - - 1 LARVAE Number of Records 1 1 4 1 2 Larval Period 36 30 --28 27 24 -- Larval Days 36 30 112 27 48 2 2 1 5 4 5 12 6 2 48 Number of Records 5 8 23 22 21 19 18 17 16 15 -13 PUPAE 46 44 21 95 72 85 192 90 26 924 Pupal Days 40 - Pupal Period 8 7 56 28 --- -- 9 ------ 50 *Date of laying not observed. Incubation period: Weighted average Maximum Minimum Larval period: Weighted average 6 168 5---------------- 45 309 Days 7.54 14 5 5----------------------------- 19.25 Maximum -------------------------------Minimum ------------------------------Pupal period: Weighted average ---------- 36 13 6.18 Maximum Minimum 88-------------------- 5 5-------------------- 33 To check the results in Table V a similar average of 51 records of complete. development of the first generation shows that 34 days are necessary from egg deposition to adult transformation. This is shown in Table VI. TABLE VI Complete Development of First Generation, Egg to Adult Development Days Total Development Number of Groups 1I-------------------56--------------56 1 1 ----------------------------------- 52-----------------52 4--- 1 ------------------ 48-----------------48 46-----------------46 ------1 2 ------------------- 45-----------------90 4 -------------------- 3------------ ---- 172 1------------------- 42----------------42 3 ----------- -------- 41---------------- 123 40----------------40 1 -----------------38 1 ------------------ 3---3---------------3 1 ---------------1 ------------------- 35-------------1 ------ 32 --- --3-8----------- 2 11 11 ------ 32 31-----------------62 308_- 28________ ---- 308 -- 27 -- - - - - - - - 81 3-1 - - - - - - - - - 2 - -- - - - - - - 26 1 ------ :------------25----------------25 1747 51 Complete development: - Days Weighted average ---------- ----- 34.2 Maximum - - - - - - - - - - - - - - - - 56 Minimum --------------------------------- 25 Because of the number of records involved 33 days is probably more nearly correct. 34 TABLE VII Egg Record of First Generation, 1921 Beetle 4-nn Q 126 24B ----6/25 46--------6/10 6/30 6---6D 48------6/9 6/10 49 59 6/15 60--------6/10 66 ----1123* - 8/12 9/14 13 617 8/24 12 33 ---------6/22 9/18 8/31 7/22 7/23 8/1 8/18 6/24 6/18 7/8 10/26 35 12 12 19 27 5 5 7 1603 665 671 942 1507 307 238 263 7/26 6/29 7/10 7/12 7/24 31 19 10123 33153 44 5I9 4I8 5 67 42 69 16 6/20 6/14 6/27 Totals Averages 1 I____i15 135 6813 1 163 1 18.1 1 757 1 I 320 35.5 Earliest date on whjch first generation laid eggs--**June 1 Latest date on which first generation laid eggs -- - October 26 Days Egg laying period for one female: Average----------------------------------35.5 Maximum ---------------------------Minimum-8 Number of. egg groups laid by one female: Average----------------------------------15 Maximum--------------------------------35 Minimum--------------------------------5 Number of eggs deposited by one female: Average---------------------------------757.0 Maximum--------------------------------1603 Minimum -------------------------------- 238 Number of days required by female to lay 1/2 her eggs - 18.1 Second Generation The incubation period, time required for larval development, and the three parts of Table VIII. According to the weighted average time required in the egg, larval, and pupal stages the total period necessary for a second generation beetle to develop from deposition of egg to pupal period are tabulated in the formation trans- in breeding work until September 18. No record was kept of the number of eggs previously laid and, therefore, the record was left incomplete. **The female laying these eggs escaped after 9 groups of eggs were laid and is not included in the above table. *This of adult would average 28 or 29 days. female No. 1123 matured August 9 but was not used 35 TABLE VIII Development of Second Generation Number of Records EGGS Days Incubation Period 14-----------------14 1 -----------------1 ------------------- 13----------------13 9-----------------9 1 ---- Egg 4 -------- --- ----- --- 32 300 9 50 --------------- 7---------------63 6------- 25 ----------------- 5*LARVAE Larval Period ---- 125 91 -Number of Records 1----------------3 1 ------- 556 Larval Days 3 ----------------- 18----------------54 10 ---------- 17---------------- 170 19 -------------------- 6---------------- 304 11 ------------------- 15--------- ------- 165 14----------------- 14 1 ---------1 - - - - -- - - - -13-----------------13 829 50 PUPAE 27----------------- 27 25 ---19-----------------57 Number of Records 2 -------------------- Pupal Period - -- - - Pupal Days 8----------------16. - 42 7- - - -6- - -- - -- - 132 5-----------------80 270 22 6 16 ---------46 Incubation period: Days Weighted average--------------------------6.1 Maximum-------------------------------14 5 Minimum ------------- ------------------Larval 16.58 Weighted average ------------------------Maximum--------------------------------27 Minimum---------------------------------13 Pupal period: period: Weighted average-------------------------Maximum -------------------------------Minimum---------------------------------5 5.87 8 A weighted average for complete development of the second generation, as shown in Table IX, is about 28 the days or practically VIII. stages ed averages for thethe sameinasTable sum of the weight*Date of laying not observed. 36 TABLE IX Complete Development of Second Generation, Egg to Adult Period for Number of Records Total Development Development Days 31-----------------62 2 -----------------3 ------------------ -30-----------------90 29-----------145 5 --------------- --17 ------------------- 28-- ------------ 476 14 ------------------- 27------ ------378 7 --------26----------------182 48 1333 Complete development: Days Weighted average ------------------------ 27.77 Maximum ---------------------- -----31 Minimum ------------------------ ----26 TABLE X Egg Record of Second Generation,-1921 Beetle 44-4 Zt E- Z F5 3A1 - 3A8 -4A 24B7* 24B1* - ------ 7/5 7/28 7/23 7/26 9/12 9/3 8/31 8/3 11 23 21 679 1308 1061 ____________ 7/16 8/17 8/10 11 20 18 121 46 42 8/18 7/26 Totals -I I I Averages 155 3048 1 18.31 1016 1 I 49 ( 109 I 16.331 36.3 * Escaped. Earliest date on which 2nd generation laid eggs Latest date on which 2nd generation laid eggs Egg laying period for one female : Days Average---------------------------------- 36.3 Maximum------------------------------ 46 Minimum --------------------------------- 21 Number of egg groups laid by one --**October --- July 5 26 Average ---------------------------------- 18.3 Maximum--------------------------=------23 Minimum --------------------------------- 11 Number of eggs deposited by one female : Average--------------------------------1016 Maximum- ------------------------------ 1308 Minimum -------------------------------- 679 Number of days required by female to lay 1/2 her eggs---6.33 -female: * *Record taken from stock cage. 37 Third Generation The incubation period, time required for larval development, and pupal period are shown in the three parts of Table XI. According to the weighted average time required in the egg, larval, and pupal stages the total period necessary for a third generation beetle to develop from deposition of egg to transformation of adult would average about 30 days. TABLE XI Developnment of Third Generation EGGS Number of Records Incubation Period Egg Days S------------------- 8-----------------8 6 ------------------ 7-----------------42 32 -----------6----------------192 8 -------------5*----------------40 47 282 LARVAE r Number of Records Larval Period Larval Days I-------------------33-----------------33 1 --29-----------------29 1 ----- -----------20-----------------20 2 ----- ----------- 19----------------38 12 ---11 ------------------6 ----------------3 ----------------37 18----------------216 17----------------187 1 - 96 15-----------------45 664 PUPAE Number of Records Pupal Period Pupal Days 1 ------------------- 16-----------------16 2 16 ---------------------------- -------- 22 96 5 -------------------- 7-----------------35 6----------------- 10 5------------------5 -------50 34 219 Incubation period: Days Weighted average---------------------___----6.0 Maximum Larval --------------------------------- Minimum ---------------------------------- 5 Weighted average------------------------- 17.94 Maximum ----------------------------- -- -33 Minimum --------------------------------- 15 Pupal 8 period: Weighted average--------------------------6.44 Maximum--------------------------------- period: Minimum --------------------------------*Date of laying not observed. 16 5 , 38 A weighted average for complete development of the third generation, as shown in Table XII, is a little over 29 days or nearly the same as the total of the'averages. for the different stages inTable XI. .TABLE XII Complete Development of Third Generation, Egg to Adult Number of Records Total Development Development Days 1 ------------------- 404--0 1 ------------------- 35-----------------35 1 3 - - - -- - - - -- - - - -- - - Period for 3 2 -- 10-------------------9 =290 12 -----------------28336 2 ------------------- 27-----------------54 34 ________________,,,,2____100 34 10 4 ------------------ 31 ------30- 32 93 120 __ Complete development: Weighted average Days Maximum ----- 29.4 40 Minimum--------------------- TABLE XIII Egg Record of Third GenerationBeetles Beetle M = 4-4 Q /c 3A11____ 3A12____ 8/11 8/13 9/10 3A14 8/15 9/9 7 378 8/20 5 25 38 16 884 8/31 9 7 8/12 9/19 3A15 8/21 8 19 8/13 9/1 7 397 3A16--__ 4A04____ 10/5 10/30 2 125 10/17 12 25 4 20 4 267 10/4 9/30 10/20 4A14 __ 28 268 10/9 I 9/29- 10/27 5 24B71 1 70 13791 _____ 741X211 ___1 Totals -1____J8.7 I 473.8!1 19.25! 26.3 Average -I Earliest date on which 3rd generation laid eggs _-_-_--August 11 Latest date on which. 3rd generation laid eggs _-_-_October 27 9/8 14 15 ,645 827 8/25 8/25 F14 12 30 26 10 Egg laying period for one Average _ M aximum - - - - - - - - - - - - - - - Minimum ------------------...-"----- female: Days 26.3 38 19 NTimber of egg groups laid by one female: Average----------------------------------8.7 Maximum-------------------------------16 Minimum---------------------------------2 Number of eggs deposited by one female: Average-473.8 Maximum ---------------------------884 Minimum--------------------------------125 Number of days required by female to lay '/2 her eggs - - 9.25 Fourth Generation The incubation period, time required for larval development, and pupal period are shown in the three parts of Table XIV. According to the weighted average time required in the egg, larval, and pupal stages, the total period necessary tor a fourth generation beetie to develop from deposition of egg to transformation of adult would average nearly 34 days. TABLE XIV Development of Fourth Generation EGGS Incubation Period Number of Records 1 -------1 16----6 -2 ------------------ 15 1 ----------------- Egg Days 1---------- 30 - 1 99-9 -----------------1 7-----------------14 2 --------22 -------------------- 6---------------- 132 227 30 14-----------------14 12 - --------------- 12 LARVAE Larval Days Larval Period Number of Records 38 - - - - -- - - 38 --1 - - - - -19---------------- 19 1 ----------3 - - - - 11 --- ----- - --- - 17---- - - - - - 187 19 3- 18 - - 16 -- - - - - - - PUPAE 48 346 Number of Records 1 ------- Pupal. Period ---- Pupal Days 18-----------------18 1 - - - - -- - - - - 15 =- - - - - - - - 15 - --- 13-- - - - - - - - 26 2 ----16 --------2 ----------------9 ------------------- 6-----------------54 3 ------------------- 5------------ ----- 15 18 144 40 Incubation period Days Weighted average -------------------------Maximum ------------------------------ 16 Minimum---------------------------------6 Larval period: Weighted average-------------------------18.2 Maximum------------------38 Minimum---------------------------------16 Pupal period: Weighted average--------------------------8.0 Maximum--------------------------------18 Minimum----------------------------------5 7.5 as shown in Table XIV is due to presence of late incu- The longer time, 34 days for complete development, bation and larval records of individuals that had no chance to mature. The weighted average for complete development of the fourth generation, as shown by Table XV, is nearly correct for late maturing beetles. TABLE XV Complete Development of Fourth Generation,-Egg to Adult Period for Number of Records Total Development Development Days 1 ------------------- 44-----------------44 2 1 ------------------- 32--------------32 1 ------------------- 31-----------------31 2 ------------------- 30-----------------60 8 ---- -- - - - - ------------------- 36-----------------72 29-- - - -- - - - 3 ------------------18 28--------------- 84 232 555 Complete development : Days Weighted average------------------------- 30.83 M aximum - --- - - - - - - - --44 Minimum --------------------------------- 28 Most of the beetles of this generation entered hibernation without depositing eggs, but the few that did lay were quickly through, or were apparently very reluctant to oviposit so late in the season. 41 TABLE XVI EggRecord of Fourth Generation Beetles Beetle 4-4 4. 'Q _________ 3B9/23 a Z 2 n H 141 Q Z -1 Z.E 3 1 9/26 130 2 9/27 9/26 4C------_ 5 9/30 239 4 10/29 9/26 4D _______ 7138 510 8 Totals --12.66 1 2.6 170.0 Average - -1 date on which 4th generation laid eggs.September 23 Earliest Latest date on which 4th generation laid eggs - - - - October 29 Days Egg laying period for one female: Average----------------------------------12.66 Maximum-----------------------------Minimum--------------------------------2 Number of egg groups laid by one female: Average---------------------------------2.6 Maximum-----------------------------Minimum---------------------------------2 Number of eggs deposited by one female: Average---------------------------------170 Maximum--------------------------------239 Minimum--------------------------------130 Number of days required by female to lay 1/2 her eggs 9/26 9/23 33 2 2.3 ____2.3 SUMMARY OF DEVELOPMENT TABLE XVII Maximum and Minimum Records of Complete Development Stages and Generations, 1st Gen. Max. IMin. by Min. 2nd 7 Gen.j 3rd Gen. 4th Gen. Max. Max. 4 j Min Max. Min. Egg-----------------First Instar---------- 12 9 6 3 6 3 7 3 6 3 61 6 313 4 4 Second Instar----------8 Third Instar----------10 Fourth Instar----------9 8 Pupa 3 3 5 5 3 4 6 7 3 3 6 5 4 3 8 15 3 4 5 6 8 18 3 4 6 6 36 Total larval period No. days for com -I plete 14 25 1717 31 15 26 1181 15L 19] 16 40 27 44 28 development'. 565 FOOTNOTE :-The average incubation period of eggs of the 5th generation was 10.5 days with a maximum of 16 and a minimum of 8 days. With the exception of one record of 27 days for development of larvae there are no other records on this generation until the mid-winter observation when adults were found to have matured in the insectary after a killing frost occurred. 42 TABLE XVIII Summary of Weighted Averages Showing Period for Developmnt of Stages in Each Generation 1st Gen. Days Egg IGen. IGen. IGen. IGen. jDays JDays IDays (Days I 6.10 16.58 6.0 17.94 2nd 13rd 4th Av. Pupal ------------- --6.18 5.87 I 6.44 8.0I 6.36 Total days, egg to adult 32.97 130.38 +,33.76 129.59J The sum of the general averages or the period for total development is 29.59 days. Larval ---------------- ------------------ I 7.54 19.25 128.55 7.56 18.2 6.50 16.73. TABLE XIX Snmmary of Weighted Averages Period for Complete Development First Gen. Second Gen. Third Gen. Fourth Gen. 34.2 days 27.77 days 29.40 days 30.83 days Showing General average period for complete development- -30.70 days transformation of the adult may be considered, The average period from deposition of the egg to as 30 days. fore, there- 43 TABLE XX Summary of Generations Hibernated Beetles Hibernating adults began to appear---------------March 15 First eggs deposited ----------- Half of beetles emerged by-----------------------April 15 Average feeding period before laying eggs----------15 days Half of oviposition period for hibernated beetles -- - 26 days Maximum infestation of hibernated beetles occurs - - - May 26 Last eggs deposited------------------------------July 31 Last adult died--------------------------------August 5 First Generation Average development----------------34 days. Adults first appeared-----------------------------May 23 First eggs deposited-------------------------------June 1 Average feeding period before laying eggs----------10 days Half of oviposition period------------------------18 days 27 Maximum infestation of first generation occursLast eggs deposited----------------------------October 26l Second Generation Average development---------------------------28 days Adults first appeared ----------------------------- June 29 First eggs deposited --------------------------------July 5 Average feeding period before laying eggs -- -- -- -- -- -- 8 days. Half of oviposition period--------------------------16 days. Maximum infestation of 2nd generation occurs--------Sept. 17 Last eggs deposited -------------------------------- Oct. 26. Third Generation Average development-----------------------------_29 daysAdults first appeared ------------------------------Aug. 2 First eggs deposited-------------------------------Aug. 11 Average feeding period before laying eggs ---------- 13 days. Half of oviposition period-------------------------9 days. March 22 July Maximum infestation of 3rd generation Last eggs deposited-------------------------------Oct. Fourth Generation Average development----------------------------- -------------- Nov. 31 2723 9 9 days. Adults first appeared-----------------------------Sept. First eggs deposited------------------------- ----- Sept Very few beetles lay eggs in fall. 44fi Table XXI Graphic Summary of the Occurrence MARCH AOOIL MlAY za of Generations AUGUST SPT.OCT. JUNC JULY HIF-ENATED BS=TLS LO GDt~NC EGGLAYING 13r GENERATION LUG LAYING PERIOD 3, GENERAThON FOG 15 23 29 3 LAYI NQ PEP .10D 4w.GUNCRATION EGG AYI NG EGG LAYING PERIoD Oviposition Records of Generations -egg An average of 52.9 eggs was found in a total of 602 groups containing 31,895 eggs. Usually they are laid on the lower surfaces of the leaves of beans, but surare sometimes, though rarely, found on face. Two egg groups may occur on the lower surface of one leaf, although other .uninjured leaves without eggs are present on the same plant. Eggs have close proximity also been found on non-food plants to the normal host. Even glass, soil, wire, paper, cheese cloth, wood, and the stem of a bean plant have been used by females as places to deposit eggs. The eggs of a typical group are usually laid in irregular rows and close together. Scattered eggs in one group sometimes occur and may cover an area 13/s inches the-upper in by 34 of an inch. A summary of the egg records of the different with complete records are included, excepting six which entered hibernation after beginning to lay. Many adults entered hibernation without laying; none of -These are included in the following summary. erations is found in Table XXII. Only those females gen- 45 TABLE XXII Summary of Egg Records of all Generations, 1921 0 No. days Beetle for- 6S .~ .~ one female to lay *1/2 All eggs, Z Hibernated 1st Gen. ____ 2nd Gen. 3rd Gen. 4th Gen. ~ 18.3 8.7 2.6 ~, 14.0- 755.515.0 .757.0 1016.0 473.8 170.0 eggs_ 26.1 18.1 16.33 9.25 2.3 ____J - ----3 9/23-10/29 Totals-----------1 36! 4/14-10/291 Weighted average I112.5 *Data used in Table XX. Number of eggs laid by one Weighted Minimum ----- 3 ------ 8 13 4/14- 7/31 9 6/ 9- 9/14 7/ 5- 9/12 8/11-10/27 48.3 35.5 36.3 26.3 12.66: 1 1 ____1______ 666.0 36.24 Maximum (Table VII)--------------------_1603 (Table XIII) average ------------------------ female: Days 666 -------------------- 125 Number of egg groups laid by one female : Weighted average------------------------- 12.5 Maximum (Table VII)------------35 Minimum (Table XIII)------------2 Period required by female to lay all her eggs : Weighted Minimum average------------------------(Table XVI)--------------------36.24 Maximum (Table IV)---------- -- 92 2 Before depositing eggs it is necessary for females take food, after which a short time elapses until eggs. are laid. Young adults do not begin to feed until 1 /2 to 3 days after transforming. Among 17 beetles that passed the winter of 1920 the interval between takingof food and laying of eggs averaged 12.3 days. An to~ ceptional interval of 43 days occurred in the case of* ex- one hibernated beetle, but because of the unusual length of time (21 days being the next longest interval) the record was not included in the above average 46 TABLE XXIII interval Between Transformation to Adult and Deposition of Eggs No. females Maximum in record Days Hibernated 17 I *21 1st Gen. ----- 9 13 2nd Gen._____ 6 17 Minimum Days *7 8 6 Average Days *12.3 10.5 7.8 3rd Gen. 4th Gen. in spring. 8 4 24 17 9 14 Days 13.3 15.5 of eggs *Intervals between taking of food and deposition Average interval ----------------- 11.7 Maximum 21 Minimum---------------------6 It is possible for some of the beetles to live 29 days -after emerging from hibernation without taking food and then revive, mate, and lay fertile eggs if brought into the presence of food. Later generations are not capable of such endurance. Observations of two females showed that one was -capable of laying 22 eggs in 193/4 minutes with a maximum interval of 2 minutes and a minimum of 1/2 a minute between eggs. The other female laid 25 eggs in 69 minutes with a maximum interval of 41/4 minutes and a minimum of 1/2 minute. These observations were taken on April 5 and 6 while the females were ovipositing upon wire of the cage. At the faster rate it would take a little over three-fourths of an hour for a beetle to lay an average group of 52 eggs. 47 TABLE XXIV Average Number of Egg Groups per Beetle Each Month for Each Generation cU) Month Z"_ Wi Ws x Hibernated Beetles April----------May----------- June ---------July ---------August ------ _- 23 13 4 2 14 584 250 92 7 1154 221 29 117 71 27 1 39 0 244 1 1 6.21 8.56 9.09 0.00 6.34 First Generation June ----------July-----------August September 12 172 October 9 5 4 I-_ I { 214 82 21 48 84 8.37 11.70 3_1 530 I 37 8 4 I I 13.98 181 4.00 10.24 7.74 I Second Generation July -------- _( August __ September 1 6 5 2 72 110 35 217 2912.48 442.40 _ __ 78 10.78 4.28 ThirdI Generation August---- September _ October ------ 11.4 5 1 I 7 105 391.4 3 I I 104 93 302 1 I 22 9 70 I I 6.34 3 6.95 Fourth 'Generation1 September_-__ October --- 4 3 51 94 7 I 145 INOTE.-Explanation of above Table : In April there were 14 beetles (Hibernated adults) having 221 "egg laying beetle days" during which 29 egg groups were laid. If 29 egg groups were laid within 221 days, 3.93 egg groups will be laid within 30 days. 1 2 I I 4.11 .65 9 1.86 48 Although the first egg group was found in the field March22 the breeding work did not begin early enough to obtain data regarding the number of egg groups per beetle for March. The principal egg laying period for hibernated beetles is May and June, the maximum record for a single beetle in one month being 12 and occurring in June. Although the highest individual average record was made in July, this is discounted by the fact that 75 percent of the hibernated females have died by the end of June. Among first generation beetles oviposition begins in June and is especially abundant in July and August; 16 egg groups laid in July being the maximum monthly record for a beetle of this generation. The main oviposition period of second generation beetles is reduced to two months, July and August. All the second generation adults used in the breeding work were among the first to transform and the records of these did not last until October. A female of this generation laid 17 egg groups during August, which is the maximum monthly record for any beetle in the work of 1921. The main oviposition period of the third generation is August, when this generation begins to lay. Ten egg groups laid in this month is the maximum for the third generation. In 1921 eggs were found in the field as late as October 28. The first and second generations each averaged 10 to 11 egg groups per female each month of their existence. The average for each of the hibernated and third generation females was 6 to 7 egg groups for each month of existence. TABLE XXV Maximum Number of Egg Groups for any Female in One Month Hibernated 1st Gen.. 2nd Gen. 3rd Gen...----4th Gen. April May 4 11 .. June 12 9 _ July 11 16 11 Aug. 0 15 17 10 -- Sept. Oct. 4 4 8 2 4 0 4 2 Although some of the hottest weather of the summer comes in September, beetles instinctively begin to refrain from egg laying even though food is plentiful. In Table XXIV it may be seen that the average number of egg groups for each female decreased in September by about 50 percent from the number laid in August. 49 Only hibernated beetles were active in April and" May. Two generations of adults including hibernated beetles were active in June. Three generations laid eggs in July and August, and 4 in September and October. The peak of egg production occurred in the month of August, but both July and August were outstanding months in regard to deposition of eggs. TABLE XXVI Relative Abundance of Egg Groups in the Field, 1921 NUMBER FEGG GROUPS APmL Fi'NAUD VIAY JUNC JULY I. 2D. 3.'.' t AUGU~ST TlN CF9IEr. n 3R0_6([N" UDT. A..'.'6U6" 3 NCCN GCN" OCT S.GEN. 2NO 6VU ",.G9U( LAID U BRT9A'rUI HI9'NATU I) s. GEN. 1YI UT . GN. GUN - 37.79 3'. 30 /;007 15 16.93 Relation to Meteorological Conditions Practically all observations for recording oviposition by beetles were made at least once every 24 hours throughout the season. Five hundred and forty-one records of egg deposition were made in this manner.. Of this number 73 percent were made in the morningand 27 percent in the afternoon. Female beetles were observed in the act of laying eggs 112 times out of the 541 instances when eggs were recorded. 50 TABLE XXVII Egg Laying in Relation to Time of Day Positive observations All observations made within 24 hours having definite time 140 Hibernated First Gen.------143 58 Second Gen. Third Gen. 46 Fourth Gen. 7 82 33 222 176 20 26 6 4 2 4 8 5 36 39 11 18 3 69 64 10 8 13 0 4 1 0 3 1 1 3 3 0 18 18 1 Totals Percent ________ _______ 3941147 73 27 541 100 [60 67 15111 19}112 13T1017 100 The 112 positive observations are tabulated in four groups according to the time of the record. Sixty percent of these positive observations occurred before 9:30 A. M. This is the only important conclusion that can be drawn from Table XXVII, for upon analysis it will be seen that the same relative proportion of 73 total and 27 exists between the morning and observations. Furthermore, 20.8 percent of morning observations were positive and 20.4 percent of the afternoon observations were positive. Thermohygrograph records made in connection with the life history work and correlated with the positive observations of egg laying show that the maximum range in temperature when eggs were deposited was 26 degrees or. between 65 and 91 degrees F. afternoon TABLE XXVIII Egg Laying inRelation to Temperature Temp. before Temp. after 9:30 A. M. 9:30 A. M. TepP.M Temp._P._M_ Max. Hibernated---------79 First Gen.-------1 Second 82 - Mmn. 76- 72 72 Max. 79 91 Min. 65 75 Max. 85 90 __ Mmn. 77 74 83 -- Gen.--- Third Gen.---Fourth Gen. ______ 80 77 90 80 89 87 70 - 88 79 83 79 89 A correlation of the positive observations of egg laying and the records for humidity show that the maximum range was between 40 and 95 percent. 51 TABLE XXIX Egg Laying in Relation to Iumidity* Humidity be- fore 9:30 AM ter 9:30 AM Humidity af- Humidity in PM Max. Mn. Max. Mn. Max. Min. 67 49 90 70 67 Hibernated---------74 91 44 60 70 45 First Gen.----__-_--87 45 53 43 75 88 71 Second Gen. 40 52 53 64 72 95 Third Gen. ------Fourth Gen. __--- --61 61 .-on 75 observations, or 67% of the positive observations. *Based Fertility Only eggs laid by paired females were included in the records of fertility. Entirely infertile egg groups were found to occur in all generations and also groups of eggs that were 100 percent fertile. The fact that gronps of infertile eggs were laid at all is remarkable because all of the beetles were paired. A summary of the percentage of infertile egg groups shows a general increase in number as the season developed. Before becoming infertile one hibernated female laid as iany as 11 groups containing fertile eggs without mating in the spring. The fertility of the hibernated beetles and those of the first and second generation was about the same. Only about a third of the eggs of the third generation were fertile and the small number of eggs laid by the fourth generation was beyond considera~ tion. TABLE XXX Summary _________Egg of Average Fertility Groups of Each Generation Eggs Hibernated First Gen. 101 Second Gen. - 48 Third Gen. _ 48 - ~ 88 1 4 12 17 3 1 11.8 4.5 2.0 Fourth - Gen. Totals - - _______1 4 289 35.4 75.0 J1371 --- Average %_--1 Fertle 1 1 12.8 Infertile egg groups egs7 ---- 5330 2675 2550 261 1 15720 1:11 4904 3529 1 n63.5 35201 66.0 1981I 929I 36.4 301 9989 {_ _ _ 71.974.0- 11.463.5- 12.8% 52 Fertility of the eggs of the Mexican bean beetle is greatest in' the months of June and July, the highest percentage occurring in July among eggs of the second generation. TABLE XXXI Average Percent Fertility of each Generation by Months June July Hibernated 62.6 77.6 68.7 First Gen. 73.2 68.0 Second Gen. __ ---- I 83.4 Third Gen.----------------_- -_- April May 72.0 Aug. 51.1 Sept. 60.1 23.1 79.9135.0 32.2 Oct. Fourth Gen. __ --_- ---11.4] The maximum and minimum records of fertility for all the eggs of a single individual in each generation are recorded in the following table: Maximum TABLE XXXII and Minimum Records of Fertility IN. females Percentage fertile in records Maximum Minimum 13 88.8 1 61.6 13 96.8 1 29.7 7 89.5 I 31.6 8 68.7 I 5.5 71.2 41.2 Hibernated First Gen. - Second Gen. Third Gen. - -- Proportion of Sexes Sex of Over-wintered Beetles The sex of beetles emerginlg from artificial hibernation was obtained only during the latter part of the emergence period. The proportion of sexes of those emerging from natural hibernation was obtained by noting in the field from time to time the sex of the beetles throughout the emergence period. The results appear in Table XXXIII. Sex of TABLE XXXIII Beetles Emerging from Artificial Hibernation Year 1921 1922 Year 1922 _ _ Sex Period No. Beetles 188 251 No. Beetles Males 65% of 4/21-5/19 4/20-5/ 1 Period 4/14-5/11 56% Males I I Females 35% 44% Females Beetles Emerging from Natural Hibernation 160 1 30% 1 70% The large proportion of males. surviving artificial hibernation where conditions were probably not en- --- I I 53 tirely satisfactory is an indication that the male has more power of endurance. It is worthy of note in connection with the proportion of sexes among beetles emerging from natural hibernation that most of the beetles were collected before the 1st of May and that the proportion of sexes among beetles taken after that time was nearly equal. Possibly a majority of the males remain with the females in winter quarters until the heavy emergence takes place. Sex of Later Maturing Beetles The data regarding sex of beetles maturing in 1921 were obtained from adults that developed in the breeding cages. The sex of all beetles developing was not determined but the proportion of males and females among 1298 beetles in which the sex was determined was very nearly the same as shown in Table XXXIV. TABLE XXXIV Proportion of Sexes May June July Aug. Sept. Total Percent M. F. M. F. M. F. M. F. M. F. M. F. M. F. First Gen. _ 10 10 103 138 Second Gen. - _-7 8 Third Gen. __-_59 Fourth Gen. __--1 341 48 65 55 38 40 89 107 52 75 102 62 ------ 185 236 41 213 211 98 161 173 62 57 44 56 50 50 48 52 53 47 57 TOTALS 101 101110 1461 991103:18612221 2161 196162116771 481 52 Total number of beetles ------------ 1298 Males ---------------------------- 48% Females --- 52% Duration of Life All the beetles that passed the winter of 1920-21 in the hibernation cage were collected in the field in October, 1920. The maximum period for a hibernated beetle to live after collection was 293 days, 121 of which were spent after emerging from hibernation in the spring. In the first generation, one male entering hibernation had already lived 100 days up to November 3. There was not much difference in the length of life of males and females; the greatest difference averaging 20 days longer life for males among over-wintered beetles. The data in Table XXXV is based upon the records of beetles that died naturally. 54 TABLE XXXV Average Length of Males Life Females Beetle Hibernated 1st Gen. 2nd Gen. 3rd Gen. -- - - No. Beetles 6 3 2 6 4th Gen. ,.. Total _ ____ 1 18 I No. Days(No. Beetles No. Days I 252.0 13 270.8 9 ( 56 63.3 54. 3 55.5 46.6 5 35.3 23.( 407.0 30 44 7.9 Days Length of life of overwintered adults: Males-----------------------------------270.8 252 Females----------------------------Length of life of adults of other generations: Males------------------------------------44.6 Females----------------------------------52.8 Effect of Starvation To determine the advisability of delaying the planting of beans with the object of starving the early emerging beetles, starvation tests were carried ont with 57 beetles which were kept inside a glass jar covered with cheese cloth. Most of the time they rested. If the death rate of these is an indication of what wonld occnr in nature, 85 or 90 percent of the beetles may be expected to die within two weeks after ing if food is not found. Of 37 beetles on hand April 1, 67.5 percent died in 7 days. emerg- TABLE XXXVI Ability of Over-wintered Adults to Endure Starvation Date 1921 April 1------ Living Dead 0 Date 1921 May 7 8------ - 37 14 April 28 4 28------ 1 12------ 5 30------ 0 1 13------ 4 15------ 4 0 0 18------ 4 to 0 29----4 2 2** 30**__ *Able to fly. * *Food provided and beetles laid eggs May 13. 9------ 12 23 9 2 3 --17------ 3 20 Living Dead 0 21----1 25------ 1* 17 2 0 0 1 55 In another experiment 31 beetles were confined with grass and white clover. The soil in which these plants were growing received excess moisture twice a day. The white clover was considerably eaten and the grass was also eaten in several places; but evidently the food did not contribute much to a longer life for 28 percent of the beetles died in 6 days, 53 percent in 13 days, and 89 percent died in 22 days. An environment possessing greater humidity than that to which an insect is normally accustomed may tend to cause the insect to change its habits and increase the variety of its food plants. One fresh molted fourth instar larva was confined without food May 25 and was alive after 6 days but died on the 7th day. Mortality When eggs collapsed and did not hatch it was assumed that they were infertile. The developing embryo in some of the fertile eggs failed to break the shell and when it succeeded in doing so the young sometimes failed to get out. The percentage of mortality among developing larvae was highest between the time of hatching and the second molt. Of 107 newly hatched larvae that were carefully cared for 41 percent died or were lost before the second instar. An additional 18 percent were lost before they transformed to adults. Some of the first instar larvae were occasionally found dead on leaves without apparent cause. In the fields rain beat some of the young larvae off the plants. Even live adults were occasionally found stuck in the soil, as it hardened after a severe rain. In general the length of life of beetles was shortened in proportion to the increase of activity among them. TABLE XXXVII Mortality of Females Beetle Hibernated 1st Gen. _ 2nd Gen. 3rd Gen. 4th Gen. _ - Apr. 0 - May June 10 3 1 - July Aug. Sept. Oct. Total 117 2 2 9 2 1 2 4 2 - - - - 0 0 2 5 I 4 0 5 0 1 56 HABITS FLIGHT Upon emergence from hibernation beetles soon take flight. Although having been without food while in winter quarters, they are strong flyers and may cover considerable distance if food is not found nearby. Upon liberating 50 beetles April 1, just after they 1lad emerged from hibernation, more than one-fourth took flight within ten minutes without crawling more than a few inches from the point of liberation. Most :of them flew at an altitude of 12 to 15 feet. After laying a group of eggs a female will usually leave the spot by a short flight to another plant or leaf. As the generations develop the newly transformed adults seek fresh plants on which to feed and lay eggs and if the beans are badly injured, the beetles may extend their search. Near the end of September a beetle escaped from a stock cage in which the beans were destroyed, was seen to fly sharply upwards, and pass over the peak 'of a shed at least 25 feet above ground. Although half an acre of beans was close by the beetle demonstrated its instinct to leave that vicinity because of the food shortage it had experienced. Flight in the field was common on October 22, 1921. As late as October 29, beetles were seen flying when ,the temperature was 73 degrees F. ,Observations during the winter were limited on account of location. However, on January 16, 1922, an instance of flight was observed within the hibernation cage when the temperature was 50 degrees F. FEEDING The adults feed usually on the lower surface, leaving portions of the upper epidermis, the larger veins, hand a net work of tissue resembling veins of the leaf. During the process of feeding there is a perceptible lateral movement of the whole body and as the leaf tissue is consumed the beetle exhibits a tendency to made recoveries up to a distance of 5 miles from point of liberation and J. E. Graf has reported finding beetles ed beetles FOOTNOTE: Howard, (31, P. 268) after liberating 5000 mark- in hibernation in New Mexico 7 1/2 miles from the nearest ean field. 57 turn gradually in its tracks and may eat entirely around itself if not interrupted or its appetite satisfied. When feeding injury is fresh it is possible to tell where the beetle stood when performing that function. After being subjected to the elements the vein-like tissue and upper epidermis left by the beetles become broken and are beaten out, leaving an irregular ragged hole, characteristic of Epilachna corrupta. The larvae when feeding sway their bodies like the adults with a slight lateral motion. A single feeding of larvae continues for a much longer period, one instance being observed which lasted 75 minutes. The Mexican bean beetle is still somewhat unsettled in its habits of feeding. In 1921, for example, hibernated beetles would not feed even in confinement upon cowpeas and the first record of voluntary feeding in the field was July 21. But in 1922 voluntary feeding of over-wintered beetles was first observed on cowpeas as early as May 13, about one month after the peas came up. HATCHING Following is a copy of the record made at the time of observation: May 7, 12:00, noon. Larva has just broken egg shell, gradually pushing out. Rested for several minutes before getting legs out. May 7, 1:30 P. M. Legs in view but close to the body. of abdominal segments. The Operation of getclosely ap- ting out is aided by using sucker-like apparatus which the larva attaches to inside of egg and by movements spines are pressed. May 7, 1:45 P. M. Legs are free. become free the body is bent forward slightly; the spines stand out individually, pale and transparent. After all legs are free and 'tail' is attached to inside margin of egg shell, larva rests. May 7, 2:45 P. M. 'Tail' released and larva stood on its legs on top of egg and rested. The only dark spots about the yellow larva are its mandibles which look like eyes. The process of hatching required nearly three hours. During this period, and until after the second molt, the young larva is rather delicate and very susceptible to the elements. Temperature 76 degrees F. As the legs 58 The length of time required for an egg to hatch varies One group of 72 eggs which began considerably. hatching on April 28 contained one egg from which the larva was trying to extricate itself as late as May 7. This period of 9 days is the maximum record in the work of 1921 for an egg group to complete hatching. MOLTING AND PUPATION The different stages or instars in the development of the larva are separated from each other by a molting or shedding of the larval skin, the larva first becoming inactive and partaking of no food for one to three days previous to this process. Upon attaining its growth the large yellow larva fastens itself by its anal segment to the surface on which it rests. After two or three days the larval skin splits about half way along the dorsal surface beginning at the anterior end and the bright yellow naked pupa appears, remaining half covered by the molted skin in which it is attached. The full grown larva has an instinct to rest in a place protected from the sun and weather and just before ready to transform it will migrate from a plant that is practically destroyed, or on which other larvae are feeding, and locate on the lower surface of a green leaf of some non-food plant or on the sides and roof of the cage in which it developed. As many as 32 pupae have been found on the base of a corn stalk which grew beside a row of beans. When ready to transform the larvae exhibit a distinct tendency to congregate and often a dozen or more pupae are found on the lower surface of the same leaf. The molting process requires about an hour before the larva is free from the shed skin. At first the color is lemon yellow but in about 45 minutes the spot around the eyes, small spines, joints of the legs, and plates at base of spines begin to turn brown. As the larvae develop the rate of growth varies, depending on the food consumed. In the same group some of the larvae get through molting before others begin. The period for a group of larvae to complete molting may be four days, and to complete pupation the period may be five to six days in cool weather. SThe pupa usually hangs head downward when on a vertical surface and has the power of moving in a dorso-ventral manner. In summer the pupa is lemon yellow in color; the brown markings that sometimes ap- 59 pear thereon and the black spines on the larvae being due to cool weather. ADULT When the newly transformed adult crawls out of the pupal skin it is entirely lemon yellow in color, no sign of black spots appearing. Within half an hour the membranous wings gradually become extended and the black spots begin to appear. In another 20 or 30 minutes the wings are folded beneath the elytra. At first the young adult clings to the lower surface of the leaf with legs fully extended. If placed on the upper surface of a leaf at this time, the beetle will crawl to the underside. In a few hours after the beetle gains strength, the body assumes a position parallel to the leaf surface, changing from its first position in which it appeared to be suspended by the legs. The first excrement seen to be voided by the young beetles was a small clear watery looking drop. Yellowish drops of excrement then pass until after the beetles begin to feed when it becomes whiteish in color. The circular whiteish and yellow excrement spots on the foliage are very characteristic where the infestation is severe. The only characteristic distinguishing the sexes, aside from the distended abdomen of the female when ready to lay, is a small notch in the posterior margin of the last ventral abdominal segment of the male. The same segment in the female is without a notch and has less pubescence. The young adults may begin to feed in 26. to 32 hours after transformation. REPRODUCTION In the field there is a noticeable attraction between the sexes, especially when the infestation is new and on fresh bean plants. During the frequent inspection of young plantings in the early part of the season the location of a lone female was marked, and almost invariably other beetles were found with her upon examination the next day. On snap beans having an average infestation of 3 beetles to 100 hills on April 25, 3 adults were found on one plant and two days later 5 beetles were found on one plant, although the average infestation had not increased. In September it was not at all uncommon to see two males clinging to one fe- 60 male and on July 9, 1921, 5 beetles were observed clinging together and hanging from one female which was holding to a leaf. A female may lay as many as 11 groups of fertile eggs after emerging from hibernation in the spring with no opportunity to mate after beginning to feed. Although this number is unusual, such an occurrence is not at all uncommon. A freshly transformed adult may mate within six days. Only the youngest females enter hibernation in the fall without being fertilized. While confined in the hibernation cages several pairs of bean beetles were observed, April 12, 1922, in actual copulation before any opportunity to take food had been presented. Fertilization of females is not necessary between the laying of egg groups, yet this is the general habit and occasionally pairs were observed in copula twice between the laying of two consecutive egg groups. Pairs were observed in connection from one hour to one hour and fifty minutes, and also when the temperature was as low as 43 degrees F. CHANGES IN HABITS From an insect having two broods in Colorado, the Mexican bean beetle immediately becomes a pest having two generations and a partial third. Including the hibernated beetles, the equivalent of three broods attack beans in Alabama. Originally the beetle came from Mexico but extended its distribution northward, inhabiting both the upper and lower Sonoran Life Zones. Now it is in an entirely new region, the Austro-riparian Region of the lower Austral Life Zone, and with this transplantation a change in habits may be expected. Chittenden and Marsh (24, p. 7) state: "In Colorado the beetles go into hibernation and remain dormant until about the middle of June. . . It is somewhat remarkable that the beetles remain in hibernation during the last days of May and the first half of June when high temperatures of 90 to 95 degrees prevail." These habits of late emergence in spring after being dormant in winter change in Alabama. The beetle is not completely dormant here as it is in Colorado. In Alabama beetles are somewhat active throughout the winter and emerge earlier in spring. In Colorado feeding is confined very largely to beans, 61 but in Alabama cowpeas and beggarweed may be destroyed and accidental feeding may occur on velvet beans, Jack beans, corn, and crab grass. NATURAL CONTROL ENEMIES Only one instance of parasitism was observed. In this case the remains of a fourth instar larva was covered with "cocoons of some braconid, probably of subfamily Euphorinae, cocoons were empty" (Rohwer). Occasionally eggs were found that had been partially eaten but it was seldom that an entire egg group was destroyed in this manner. While keeping close watch of the infestation on 51/2 acres of beans from April 15 to June 30, 1922, only two predators, Stiretrus anchorago Fab. and Megilla maculata D. G. were seen to attack the Mexican bean beetle or any of its stages. Hippodamia convergens Guer. is a very common predacious insect which fed upon eggs of the bean beetle in confinement but was not observed attacking eggs in the field. When food is scarce both adult and larval stages of Epilachna corrupta will eat its own eggs. Probably the most important of the native enemies of the Mexican bean beetle is Stiretrus anchorago Fab. a species of the Pentatomidae. This bug when attacking its prey pushes its long beak into an egg or any of the larval stages. It has been observed attacking freshly transformed adults. Activity by this species in 1922 was first noticed May 23 when attack was made upon a fourth instar larva. After such an attack nothing but the skin of the larva was left. Nymphs and adults of Stiretrus anchorago will feed on eggs, larvae, and pupae of the bean beetle. They increase and in the fall of the year they are common. The first attack of Megilla maculata observed in 1922 was on June 10 when an adult was seen eating a first instar larva of the bean beetle. This species of ladybird becomes very common in the fall. Tiger beetles and ground beetles have not been observed attacking any stage of the bean beetle. The common garden toad entirely ignored the presence of the adult beetles. Hens and chicken, will reject both adults and lar- 62 vae. Guinea hens, when passing through bean plantings, paid no attention to the beetles or larvae. The long spines of the larvae and the drops of yellow liquid exuded from the knee joints of the adults are apparently efficient in protecting the Mexican bean beetle from birds. An interesting account of the importance of predaceous enemies was published by N. F. Howard in 1921 (28, p. 19). CLIMATIC CONDITIONS A remarkable instance of natural control by heat was observed on rows of white tepary beans during one of the hot spells when the temperature was 100 to 101 degrees F. in the shade. The foliage was already partly destroyed and the remainder was turned so that only the margin was presented to the sun's rays. Great numbers of all stages of larvae were found dead on the ground. Nothing of this kind was observed in connection with the commonly grown beans. Following hard rain storms, especially when they were accompanied by rather strong winds, many larvae of all stages were beaten off the bean vines and found dead between the rows. Such storms have considerable influence in reducing temporarily the severity of an infestation. INSECTS MISTAKEN FOR THE MEXICAN BEAN BEETLE The other lady beetle which feeds upon foliage is the squash lady beetle, Epilachna borealis, Guer. a larger beetle with seven spots on each wing cover. Diabrotica12 punctata has been confused with Epilachna corrupta but the twelve spots and elongated appearance easily serve to distinguish it. The work of Ceratoma trifurcata is often abundant and causes alarm but the adult responsible is not at all like the Mexican bean beetle. Only young bean plants are injured by feeding of this pest. The Mexican bean beetle is frequently mistaken for the Colorado potato beetle, Leptinotarsa decemlineata. 63 PREVENTIVE AND CONTROL MEASURES EXPERIMENTS IN 1921 Spraying and Dusting The work of finding control measures began in July, 1921, and ended Jnne 30, 1922. The 1921 experiments were preliminary, the object being to find something that could be used with safety to bean foliage and at the same time something that would control the pest. In these experiments 22 insecticides, including the various dilutions and combinations, were used. Eightyfour applications were made to both snap beans and butterbeans. These applications were made during .July, August, and September, the hottest months of the summer. The main insecticides used with the number of treatments in which each insecticide occurred are given in Table XXXVIII. TABLE XXXVIII Insecticides used in 1921 Insecticide -Dusts:: Pyrethrum ---------------- How Used* Applications 100% to 20%------Arsenate of Lead ---------- 20% to 10%-8 100% to 33.3%-2 Powdered Bordeaux -5 Calcium arsenate ---------- 25% to 11.1% Calcium arsenate, sulphur and Lime-------------- 1-1-2----------------1-1-4 ----------------Calcium Arsenate and Sulphur ------------------ 1-1--------------------2 Sulphur------------------ 25%----------------Pyrethrum, Calcium Arse- ------- 3 19 1 2 nate, Sulphur, and Lime- 2-1-1-4_----------2 Nicotine Lime Sprays : Kilspray ----------------- 1-500------------------2 1-1000-----------------5 1-2000 Blcef40____________1-50_____________ ------------ 2% Nicotine sulphate --------- _--------9 1-20 *Where percentages indicate dilution, hydrated lime was used. In the sprays water was the diluent. After three months .of experimenting with these insecticides several promising dusts were found which seemed to control the insect but not all appeared equally safe for the plants. However, one of the. mixtures 64 clearly demonstrated its ability to check destruction by the bean beetle. Not the slightest trace of injury to the foliage occurred after 19 treatments. This mixture contained calcium arsenate, fine dusting sulfur, and hydrated lime in the proportions of 1-1-4 by weight. An interesting fact in connection with the mixture is that the calcium arsenate and sulphur were bought ready mixed and had been on hand for two years. It was obtained under the trade name "Niagara Mixture A," and was said to contain 50 percent calcium arsenate and 50 percent sulphur. The mixture used for controlling the bean beetle was made by taking 1 part of this "Niagara Mixture A" and thoroughly mixing with 2 parts by weight of hydrated lime, thereby making the proportions 1 part calcium arsenate, 1 part sulphur, and 4 parts hydrated lime. Other important results obtained from the control work in 1921 may be briefly summarized as follows: 1. None of the dusts or sprays used prevented hatching of the eggs, although egg laying was greatly retarded by several of the treatments. 2. Spraying by means of a hand compressed air pump did not prove practical. The pressure could not be kept up sufficiently to completely cover the foliage of mature plants. Also, when spraying, the extra time and labor involved was a big factor and one which prevented spraying experiments in 1922. 3. Pyrethrum produced the most immediate results, but was not effective for any length of time. Best results were obtained when used in the proportion of 1 part pyrethrum and 2 parts hydrated lime. 4. Arsenate of lead was much slower than pyrethrum in its action but far more effective in length of efficiency. When used with hydrated lime in the proportion of 1 to 8 good control was obtained, but this did not prove safe for the beans because late injury or burn resulted. When used 1 to 9 it was less effective. 5. Powdered Bordeaux had a slight repellant action to adults. 6. Calcium arsenate, sulphur, and hydrated lime was also used in the proportion of 1-1-2, containing 25 percent calcium arsenate. Three applications were made without causing injury to bean foliage. "Niagara Mixture A" was used in making this combination. Pure "Niagara Mixture A" severely burned the foliage. 65 7. A mixture of calcium arsenate and hydrated lime containing 20 percent calcium arsenate burned the leaves. Injury also resulted when used in the proportion of 14 2/7 percent. Apparently sulphur prevented injury by calcium arsenate when mixed with it as recorded in paragraph 6. 8. Sulphur had a slight repellant effect on adults when used at a strength of 25 percent in the only application made. 9. A nicotine-lime mixture containing 2 percent nicotine sulphate was not effective. 10. Black Leaf 40 as used in the spray applications was too weak. No injury resulted. 11. Kilspray is an alcoholic extract of pyrethrum prepared in the form of a heavy liquid soap, which mixes readily with water. It was found to be repellant to adults and effective against larvae in dilutions as high as 1 part Kilspray to 2000 parts of water. Filmigation Experiments The possibility and danger of bean beetles being transported in shipments of hay was demonstrated in November, 1921, by finding 6 beetles and 3 pupae in a barn containing cowpea hay. Evidently the insects had been brought in with the hay. It had frequently been noticed that the adult bean beetles were more resistant than other insects to the effects of the poison bottle. Having an opportunity to use a small room in which nursery stock was fumigated nine experiments with hydrocyanic acid gas were conducted to test the resistance of beetles, and to determine the dosage necessary to kill. The results of these experiments which were performed during the middle of December, 1920, appear in Table XXXIX. In each experiment sodium cyanide, sulphuric acid, and water were used in the proportions 1-11/2-2. The room contained 685 cubic feet. 66 TABLE XXXIX Resistance of Beetles to Fumigation _______ ________ _______Epilachnr corrupta z Q) N Q 6.9 __ 9.0 _ 1.0 1.3 40 45 70 50 - 12 6 I 3 6 10.5 8.0 9.0 _____ 10.5 7.0 _____ 7.0 8.0 1.5 1.16 1.3 1.5 1.02 1.02 1.16 45 75 75 75 60 90 45 50 45 50 55 60 65 60 4 6 6 6 19 6 6 0 3 1 0 0 0 0 With the temperature 60 degrees F'. about 1 ounce to 100 cu.ft. for an hour will probably be sufficient to kill beetles. At 50 degrees F. 1/2 ounces to 100 cu.ft. for 45 minutes may be required. OTHER EXPERIMENTS In conducting burial tests, beetles were covered with good friable clay loam soil to a depth of 1, 2, 3, 4, and 5 inches. The soil was not packed. All the beetles emerged from a depth of one inch, but f ailed to appear when covered two inches or more. In November, 1920, other beetles were submerged in water for varying lengths of time, namely, 22, 46, 52, and 70 hours. Those submerged for 22 hours recovered upon removal going the mergence tles. The 52 and 64 and all longer tests. In December additional subtests were made with partly dormant beeperiods of submergence were 12, 24, 36, 43, hours. Six beetles were used in each test but none were alive after under- of the 36 beetles recovered. 67 Experiments in 1922 Plan and Method of Work In order to more thoroughly test the most promising insecticides, the control investigations in 1922 were conducted on a much broader scale and applied to varieties of beans commonly grown in the South. These included both bush and pole varieties of Phaseolus vulgaris and Phaseolus lunatus. Infestations were taken to provide not only. a means for comparing the susceptibility of different types of beans to attack by the bean beetle, but more especially to compare the results of poison applications. When taking the infestation no effort was made to count the individual larvae but the different stages of larvae observed were recorded; also the presence of pupae, the number of egg groups, and in most cases the number of adults. Except three plats of bush snap beans which were planted in the drill all beans were planted in hills which is the unit used when mentioning the percentage of infestation. It was never difficult to distinguish separate hills of bush beans although consecutive hills frequently overlapped at maturity. In the case of the three plats planted in the drill, one foot of row is the unit. The percentages of infestations and relation to treatments were tabulated in connection with each experiment, but, except to illustrate the method, the tabulations are not recorded in the following pages. The graphic summaries, pages 81 and 89, tell the story in part. Results of experiments are briefly summarized and arranged in groups according to the type of beans, as follows: Experiments with bush, snap or string beans on 17 plats, comprising 2.53 acres. Experiments with pole snap beans or string beans on 9 plats, comprising 1.48 acres. Experiments with butterbeans, or lima beans on 2 plats, comprising .86 acre. Experiments with cowpeas on 2 plats, comprising .32 acres. The control work was brought to a close June 30, 1922. 68 Definitions A "hill," "pole," or "foot of row," was declared to be infested if examination revealed eggs or larva of Epilachna corrupta. Pupae and adults while recorded are not considered when giving the percentage of infestation as such. Pupae will not injure the plant, and, unlike the egg group, their latent power for producing injury is not necessarily confined to the plant where found. The presence of adults is not an indication of the true value of an insecticide because of their ability to fly. Where the occurrence of adults is mentioned the reference is always specific, e. g., "percentage of adult infestation" or just "adult infestation." The number of infested hills in one hundred is the percentage of infestation. Since eradication is not claimed it is possible to have a high percentage of infestation with relatively little injury, but, in general, a high infestation is accompanied by injury The presence of destroyed hills indicates loss of control. Insecticides Used Dust applications were made with powdered insecticides in all experiments of 1922. Whenever mixtures were prepared a mixing machine having a capacity of 15 pounds was utilized. 69 Following is a list of insecticides TABLE XL Insecticides used in Control and Proportion of Materials in Mixtures Percentage of Material in Mixture Insecticide arsenate--------26.66 1 Magnesium Compound 6.66 Bol-wee Compound, 1 part-Hydrated lime, 2 parts__-__ Hydrated lime -- - - -- -- 66.66 As 2 O5 - - - - - - - - - 10.66 2 16.66 Cal-Sulphur ____ ____ * Calcium arsenate---Sulphur...............16.66 Hydrated lime---------_ 66.66 As 2 O 5- - - - - - 6.66 .3 arsenate_ 9.5 iDosch Mixture, B-14, 20-10-70 Copper Sulphate-----19.5 (Monohydrated) Hydrated lime------71.0 3.8 As 2O 53 *Calcium*arsenate--------19.5 Dosch Mixture, B-15, 20-20-60 Copper Sulphate--------19.5 (Monohydrated) used: *Calcium -- *Calcium Hydrated lime---------- 61.0 As 2 O5 - - - - - - - - -- 7.8 16.66 16.66 66.66 14.28 14.28 71.42 Niagara Mixture A, 1 part--- *Calcium arsenate------Sulphur -- - - - - - Hydrated Lime, 2 parts Hydrated lime As 2 O 5 - - - - - - - - - - 6.66 4 Niagara Mixture A, 2 parts-- *Calcium arsenate---Hydrated Lime, 5 parts--- Hydrated lime As 205----------5.71 Sulphur - - - - - - - 5 Pyrethrum, 1 part-----------Pyrethrum--------------33.33 Hydrated Lime, 2 parts----Hydrated lime---------- 66.66 Pyrethrum, 2 parts Hydrated Lime, 5 parts as calcium arsenate recommend*With same ed by U. S. Department of Agriculture for boll weevil control. 1, Bobwhite Chemical Co. 2, Vaycide Chemical Cor. 3, ----specifications --- Pyrethrum-------------28.56 Hydrated lime71.42 ]Dosch Chemical Co. 4, Niagara Sprayer Co. 5, Imported. The experiments in the different groups are listed numerically by plats; the graphic summaries, pages 81 and 89, are drawn according to date that beans came gip. 70 N DINE W00OD N ~XPLKPI1 i[NT3 L 1921 tEAN.b 1.ET of Bean Plats. 120 feet. 71 Experiments with Bush Varieties of Snap or String Beans (Phaseolus vulgaris) PLAT 1, EARLY VALENTINE, .19 ACRES Beans came up April 17. Treated twice: 28 percent pyrethrum on May 14 and Cal-sulphur on May 25. Control not obtained. The beans of this plat were undersized, lack of fertilizer being the main reason. The injury caused by the beetles and larvae to these small plants increased rapidly and soon became relatively severe. The weak pyrethrum treatment was applied when the foliage was wet with dew and apparently had little effect. The arsenical application was not made until 30 days after beetles were first seen on the plat and the infestation by that time had become so heavy in proportion to the size of the plants that only slight benefit resulted. The futility of attempting to grow small undernourished beans in territory infested by the Mexican bean beetle is demonstrated by this experiment. Such beans become infested as early as any and the percentage of injury resulting to them is far greater because of the small amount of foliage they possess. In less than two months from the date of coming up the beans of this plat were destroyed in spite of the treatments, and were ploughed up by the grower. Attention is called to a comparison of yield of this plat (75 baskets per acre) with that of Plat 11 (40 baskets per acre) where undersized beans were not treated. PLAT 2A, EARLY VALENTINE, .19 ACRES Late planted; coming up May 20. These beans escaped an early infestation and were not in need of treatment until about a month after coming up. After emerging from hibernation beetles appearing in this vicinity had been attracted to Plat 1 and as long as that source of food supply held out there was practically no migration to Plat 2A, 175 feet distant. With the destruction of beans on Plat 1, and also with the maturing of the first generation beetles, there was a decided increase in the adult infestation on Plat 2A the second week in June. Very few beetles had been found on this Plat up to that time. No treatment was given. 11)1! I'Is suOi cl Tr u a koI.liain ca pia Iol> isr~ a~\\ It W \ ticslooil rt Itcotrter IloootO suctl\ l n 1 Ilt ~tl ap 1 oli if the iilllo ll cr c \ ith t Iti'0Vo jo %lctnh that m. ( oo Ooil"My carcd' tOfhll or h al arct iil,(0- tiC 11(.0 hh Ptll I ti' Iions.' r 'oN l APhi hhoi tl' pick-414 hu Ii1(41S ( 41144 1111 111141 t from4 1 441 ll 42(1rc 44'c B4 un1 Bci 44'''d 41 141 h llll comlmrc flat1 ('lulle bcoll I) time1Il t 4 IAol I'\' 1111111 1 ,o hi44-14 t io h s 11 found4 111 4 8 : s dul.II lcI4I-in from. c 1111' s;11 lii io.' U. w 4 a ' . -' .a 44 44 4,. x11. 1~I:AVV \ NXxr 1( no4 trM't((ll. ? AINE, .011 _Ao~: ompl11Iirc(( This phlit nillixb li l l ' b ill rnou ;ilmulic'4lin \4! wx illt fg - 14F4l 1( Imiii\l 11(I sim l Ph~is i l - w l Iylxi ~~iI0 etothe of 7(1 c(uiik xxittli ot 1Pi xi i:'. (1.ixl S'riioIS'~ (dOs Ni'44i1, .18 .Aches Bcu~mis (111( till '_hp'l 1:;. gI'44\iii ini 1;iii rilhx lu*t'lii((l.n Ilw~ 11 lix o114- (Ill Il41 41llI\ :A 28 (I(S, iiiii col~ilj4( \l'4 i ii ils Iicon- ilil1114'( l ix ivIl xx1whi 1w x l i lt mixNliir 14 xxw wis ( o1 Ili(' ihnil-(. ip i'(( xxni-,ii'- Ilx c o '~ic Iion14x iin.~ o lic i 44 r llc onlyx 4\ ni i M11 414 .ol1 j; X i 1 1iV unll' 4 dr~tiffirenc \iAii ICcrd iin ;is( iPsuilt xx Mu1l)1l iiic- (1 14 ;m ldr in i licul 41 thx cdl Lx third ti'uiliiieit t on 11\Lix 271 xxili ixtureIF coil- anid I~lidrlcdu lijit,. ( ;oouI coiitioI Ti ls \liitV \\fln affcctcd andl the is llt lrlly ai Ilili41 dill wh icih pro- ~-& V~J6 4w I ( II lit in ~i 7ii , St I l\\ in I t I ci II I \ I I il I I. It;)s\ ~in jicjtl (Li ia i XI XIiikw I .A ut Xli I l ( liTh lfirX ii I 111IImI 1u n iii . \lw' a by tI Il i n t 11 he ii(sillliiin viiX I I of I(Ii liL (. III lii it c Ii I lrlt.1 81 i i .08 .Aci I iiiuil o i i. o SI l I cll. (II Xjl PIt l! In hl IIi..( ia II sa ((litl 79 page 81. However, control was gained as seen by the reduced infestation. The increase of infestation on the check is shown in Table XLII, page 81. PLAT 14A, EARLY VALENTINE, .10 ACRES Early planted beans came up April 10 anl grew well. On May 11 an application of Cal-sulphur was given to the west half of the plat when the foliage was dry and ,on the following morning the same insecticide was -dusted on the east half of the plat when the The person applying foliage was wet with dew. the dust, and the hand gun used, were the same At the request of the grower no in both cases. further treatment was given. On May 13 there was an adult infestation of 112 percent on beans treated when dew was present compared with 53 percent on beans treated dry. But the most impressive result of this experiment is the final observation taken by one who did not know the plan of treatment or the insecticide used. The observation as recorded by Mr. Whitlock follows: "6/10/22. Heavy infestation, all plants destroyed except about 40 hills in each row on the west half of the plat." This half was dusted when the foliage was dry. When dew is present, especially a heavy dew, the leaves droop and hang closer to the ground. Not only is it difficult to force a cloud of dust through to the underside of the leaves but wet leaves nearest the nozzle catch and hold too much of the insecticide, thus preventing an even distribution of poison. PLAT 14B, EARLY VALENTINE, .13 ACRES Beans were planted between rows of cabbages and came up April 12. They did not receive proper cultivation. No treatment was given and no infestation taken until May 26 when they were found to be heavily infested and nearly destroyed. PLAT 14D, EARLY VALENTINE, .08 ACRES Late planted. Came up May 16. These beans were .adjacent to Plat 14B which was rapidly becoming infested. At first the beans of Plat 14D were protected because of the later time of planting; and also partly because of an early treatment with Niagara Mixture A and Lime, 1 to 2. On May 27 there was only a 4 percent infestation, but with the destruction of Plat 14B the infestation on 14D jumped to 64 percent on June 9. 80 The results of 3 applications within the following 2 weeks using the same insecticide as in the early treatment may be seen in the reduced infestation of Plat 14D, Table XLII, page 81. On June 24 only 8 percent of the plants were infested while the check showed 100 percent. PLAT 15, EARLY VALENTINE, AVERAGE GARDEN In this garden a second planting of snap beans and a fall crop of butterbeans were destroyed by bean beeties in 1921. The first planting matured without loss in yield and the following year, 1922, early beans were again planted. They came up April 12. As late as May 23 not a beetle or larva had been found on them. On May 31 an infestation of 29 percent was found. Evidently not a beetle passed the winter of 1921-22 in this garden which also escaped discovery by those emerging from hibernation. Another garden 100 yards away became infested May 10 and was completely destroyed by June 5. This varying condition in time of infestation in different gardens may be more or less regular from year to year or may vary in the same garden, depending on the proximity of winter quarters chosen by beetles. GRAPHIC SUMMARY OF EXPERIMENTS ON SNAP BEANS Explanation of Table XLII, page 81. Progress of infestation by E. corrupta in snap beans indicated by black area. Vertical lines represent dates; total time included is from April 10 to June 29; date when beans were planted indicated by left margin of stipuled area. Arrows show dates when infestations were taken. Figures on right are the number of baskets of beans gathered per acre. Lined area Plat 6A represents all rows of Plat except row 14 which is represented by black area. Treatments given have been indicated as follows: c. s.: Calcium arsenate, sulphur, and hydrated lime, 1-1-4; commercial. P.: Pyrethrum diluted with hydrated lime. 1: Calcium arsenate, sulphur, and hydrated lime, 1-1-4; home mixed. 2: Calcium arsenate-magnesium compound and lime, 1-2. 3: Calcium arsenate, sulphur and hydrated lime, 1-1-5. 4: Copper, calcium arsenate, and hydrated lime, 20-10-70.. 5: Same as c. s. Dry, dew: refer to condition of foliage at time of treatmenLt TABLE XLII Graphic Summary of Experiments on Snap Beans R13 IL MAY ui 20 l 20: 310 0 30 9 2 twy 7r I * I Pju 2, i,,xxvs P(,JI: 13r:: S, .17 A Hius in~ Junei, inl sp)i[e of the( trlafl lls, arle (direct rtsihI of the destruictioni ofh als oin Pl 1 anidi conusei(lPn miigr'atioin oI* adults1 and( Iarv c from8 thatl Pl to PlIat 2. Pi-vi 2B, Iix s the& n1(8r(st oi~r N: va s, .2 A ,s 1These. Jons wer abuout 2(1( feet nay x~e Ioii Plat 1, fr (arl- platinglu. They cam if uip ay :IV 1)1bu ver fewv ir-,[ g('nelihili~ beethles found( theriutil laitae to Plat 2ii[l had huso ~ 'ii( iIi nd 1v.(nil aduts. Oin June 1(i the ault infUs~i [011a\(s I percit In o1110wx 1 later' it hai I incrieasedl to 8(0 perenti. Pule I3(,rnns, Plat -I, 13 \Vcclcs Ohl, nfler ) Ap1)1i("alions 1 Ijcrccmit iuur Hii f irst two( Irci(811(Ii- py)\c I(III'uulI cidc(s used( were( the IUollo\\ ili made(I wit 111ach t vi separaie divisions of! 11h1itilI. The shop i u I' te asence of th ofm ( ) medii 16i, 11 ptittil chitck -wis dIIfligel 1catisc oft he 11ush liiiul il lss Ical' arch IittIlti resuti- «\ ei 18 iflchl(s to ? t of' mir):e feel (G aljtiI[ ili Thor- hi~t Ihiii feel. 11t11 ol iage wxis hlix. wN11(11 thet 15 xwI1wi dcwx \\'s 1)1(1 i thit operator uisuallyI got \\c tI intithII \\ 81st I),IiuxId Hill, Pl 1T UW li1' '1 " \ h)'s oni't* 1 l i I li ! t" ii 11an c1 1os Ii il i t)ii theIIl i '-. n o11 , (1)1) 141 tr in Pil 11)4 441ic c\ nti( thi li. c I hr I - Pi~~I~t I \S .1 A) Iulliu Its Nh~ c il i 1)4I iti i ~ 14 III ill rItI[l 1i Il 1 1114) cal I of~ i Itiw 11I:h IiioI 145 1 II4)he)4 14i444l IQ4 ]4(~ii (~ 1115 11) 5\I~ ii linlv o alijiil44 IS h i tll 441141ilt~hl~i14'154 VIt stIk' 1)11 A Ii4 application, 85 and were not destroyed until the middle of July. other treatment was applied. PLAT 8A, POLE BEANS, .16 ACRES No Beans came up April 10. Five applications of Calsulphur were made to one-third of this plat; the whole plat received the first three applications. On another third Cal-sulphur was followed by two applications of Bol-Wee and lime, 1 to 2. On the last third Niagara Mixture A and lime, 1 to 2, was used following the three All applications were applications of Cal-sulphur. made when the foliage was dry. Although the percentage of infestation had run up high it was not heavy and no injury developed. The graphic reproduction of Plat 8A, Table XLIII, page 89, is representative of all three insecticides. The check area, on June 22, had an infestation of 70 percent. PLAT 13A1, POLE BEANS, .16 ACRES Beans and corn came up May 22. Two applications were made. The first was Niagara Mixture A and lime, 2 to 5. Niagara Mixture A and lime, 1 to 2, and BolWee and lime, 1 to 2, were used on separate areas for the second application. Later infestations showed an advantage of a little less than 20 percent in favor of the Bol-Wee and lime, 1 to 2. Good control was produced by both. The check had an infestation of 88 percent. PLAT 14, POLE BEANS, .15 ACRES Beans came up April 15. This plat furnished a good demonstration of the destruction that may be caused by the Mexican bean beetle when allowed to go unchecked or when improperly treated. Although reliable insecticides were used, the first application was not given soon enough and the interval between applications was too great. The two treatments that were made saved the beans for two weeks after the destruction of those on the untreated portion but the infestation had become so heavy that it could not be reduced in time to save the beans and the ground was cleared for ploughing June 26. PLAT 14C, POLE BEANS, .10 ACRES These beans came up late, May 20, and were adjacent to Plat 14. The increasing infestation on Plat 14 gradually spread to Plat 14C. Four applications of 86 Cal-sulphur proved sufficient to protect this planting until the menacing migration from Plat 14 was over. The first application was made 5 days after the beans came up. On July 6, larvae were scarce and the foliage was in fair condition. Experiments with Pole Butter Beans (Phaseolus lunatus) PLAT 6B, POLE LIMA OR BUTTERBEANS, .43 ACRES Came up late, May 15, and had a 3 percent infestation 10 days later. Several different treatments were made to these beans, the first application being made on dry foliage June 2. At this time Niagara Mixture A and lime, 1 to 2, Cal-sulphur, and Dosch Mixture B-14, were used on separate divisions of the plat. Except for a slight increase in infestation where Dosch Mixture B-1.4 was used the percentage of infestation was lowered on all sections of the plat. For the two remaining applications dew was on the foliage. Bol-Wee and lime, 1 to 2, was substituted for Dosch mixture B-14. Otherwise the same insecticides were used. Only a light infestation was present at any time on this plat, good control being maintained. The percentage of infestation when last taken on June 26 was a little lower where the Bol-Wee and lime had been applied. No injury resulted from this insecticide although it contained 26 percent calcium arsenate. A low percentage of infestation was found June 22 on all the areas of this plat. This was due to two severe rain and wind storms which whipped many larvae off the vines. The leaves of butterbeans are small and their surfaces smooth, thereby subjecting larvae and eggs more to the violence of winds and rains. Most of them crawled back to the vines because the next infestation showed a very large increase on all divisions. On July 6 the foliage was in very good condition. Very few larvae were on the leaves but adults and eggs were numerous. On July 30 injury was apparent but none of the beans on this plat were destroyed, even after going without protection for over a month. PLYI S). P+n.t: IANI v (M B( 'I rl1IWr:_\Ns, .I:I .A(AiLS I 4 , p.' art: r1z: Ilu t. I t, iii ( d (] (IiiuI), (4114 ~I 1 11 IIrns ' S.A wXi Iicah, thoseIt 4I1cs. cx u all til lix i Ii) c Init1X of'oiitheoIi I)i4Il,(these 88 The insecticides used were as follows: Niagara Mixture A and lime, 1 to 2 Cal-sulphur Bol-Wee and lime, 1 to 2 Dosch Mixture B-14 The graph of Plat 9, Table XLIII, page 89, shows the treatments and infestation on that division receiving the poorest protection. The remainder of the plat received four applications. Except the second, all applications were made when the foliage was dry. No injury resulted from any of the treatments. GRAPHIC SUMMARY OF EXPERIMENTS ON POLE BEANS Explanation of Table XLIII, page 89. Progress of infestation by E. corrupta in pole beans indicated by black area. Vertical lines represent dates; total time included is from April 3 to June 29; date when beans were planted indicated by left margin of stipuled area. Arrows show dates when infestations were taken. Daily rainfall shown at the bottom of plate. Treatments given have been indicated as follows: Calcium arsenate, sulphur, and hydrated lime, 1-1-4; commercial. P.: Pyrethrum diluted with hydrated lime. 1: Calcium arsenate, sulphur, and hydrated lime, 1-1-4; home mixed. 2: Calcium arsenate-magnesium compound and lime, 1-2. 3: c. s.: 4: Calcium arsenate, sulphur and hydrated lime, 1-1-5. Copper, calcium arsenate, and hydrated lime, 20-10-70. 5: Same as c. s. Dry, dew: refer to condition of foliage at time of treatment. 89 TABLE XLIII Graphic Summary of Experiments on Pole Beans _.i i 90 Experiments on Cowpeas (Vigna sinensis) PLAT 12, CALIFORNIA BLACK-EYED PEAS, .17 ACRES Planted early. They came up April 15, adjacent to Plat 11. On May 16 four plants showed signs of feeding injury and an adult bean beetle was found. One application of Dosch Mixture B-15 was sufficient to protect the peas up to the first of July. PLAT 14, CALIFORNIA BLACK-EYED PEAS, .15 ACRES Planted late and near beans that were finally destroyed. The last of July the peas were heavily infested and suffering considerable injury. No treatment was applied. A plat coming up July 15, 1921, was located adjacent to beans that were later destroyed. Less than a 1 percent infestation was found two weeks after coming up, but in August the beans were destroyed and the cowpeas were heavily attacked. The ground was entirely covered by the rank growth and it would have been necessary to tramp upon and injure the vines considerably if an application were made. The peas were not treated and 7 weeks after coming up they were practically destroyed. USE OF DUSTED BEANS AS FOOD Chemical analyses of several samples of dusted beans were carefully made. The insecticide used, contained 6.66 percent As 2 05. The beans in one sample had been dusted when the foliage was dry and in another sample when the foliage was damp with dew. In each case a heavy application of dust had purposely been given. The beans from which the samples were taken were picked I hour and 3 hours respectively after dusting. Two other samples were picked from the same rows 9 days after dusting. In the meantime it had rained 1.26 inches in 24 hours. The arsenic determination was made by Mr. S. J. Marion*, using the Modified Gutzeit Method. The results he obtained are shown in Table XLIV. *Associate Research Chemist, Alabama Experiment Station. 91 TABLE XLIV Arsenic Determinations on Beans How Treated 9-29-22 Dew Dry Interval Before Picking 3 hours 9 days F Wt. Sample Analyzed 200 grams 400 grams 200 grams 400 grams Total As 2 0 3 1.37 mg. 1.2 mg. 9-28-22 1 hour 9 days 0.46 mg. 0.3 mg. In order to get a fatal dose of arsenic a person would have to eat 40 pounds of green beans which had received a heavy application of dust. However, visible traces of insecticides should be washed from beans before cooking. Ordinarily beans are always washed by truck growers before being placed on the market. SUMMARY AND RECOMMENDATIONS GENERAL SUMMARY OF EXPERIMENTAL PLATS The earliest destruction of a bush bean planting was observed June 1, 50 days after coming up; it was not treated. The plat of snap beans receiving the best protection lived about 100 days; it received four treatments. The date when the first pole beans were destroyed was June 12, 58 days after coming up. Because of possessing more foliage, pole beans are capable of withstanding a heavier attack than bush beans. Adult beetles show no preference between bush and pole beans when both are Phaseolus vulgaris. Butterbeans (Phaseolus lunatus) possess nearly the same attraction for the beetles, but the infestation of eggs and larvae develops slower. Cowpeas may be attacked and completely destroyed but in most cases where this occurred, destroyed bean plantings were very near. 92 SUMMARY OF INSECTICIDES Applications of the insecticides listed in Table XL, ,page 69, were made to areas averaging one-tenth of an acre each, as follows: 63 to bush varieties of snap beans. 46 to pole varieties of snap beans. 22 to pole varieties of lima beans. 1 to cowpeas. Six of the insecticides contained arsenic and the control resulting from their use was in proportion to the amount of arsenic they contained. A brief summary of the results obtained with each arsenical follows: Calcium Arsenate Magnesium Compound (Bol-Wee) -------------------------1 part Hydrated Lime ------------------------2 parts This mixture contains 10.66 percent As20 5 . The magnesium compound was added by the manufacturer to increase adherence of the calcium arsenate. Comparatively few applications of this insecticide mixture were made because of the high arsenic content. Eight treatments were made 5 to bush and pole snap beans and 3 to butterbeans-when the foliage was dry and when it was wet with dew. No injury or burning of any kind resulted. A safer and much lower arsenic content would be present if 1 part of the calcium arsenate magnesium compound were mixed with 4 parts of hydrated lime. Such a mixture would probably be easier to apply and would contain only 6.4 percent As 2Os. Copper Calcium Arsenate (Dosch Mixture B-15) 20-20-60 A stock mixture containing 7.8 percent As 2Os. This insecticide showed more tendency to burn than any of the mixtures or other insecticides used. Six applica'tions were made, but no noticeable injury resulted. The only trace of burning was indicated by a brown coloration which developed around the margins of injured spots or areas, especially on butterbeans. The Italian growers were inclined to favor this insecticide because of the bluish color; other insecticides appearing too much like lime. 93 Niagara Mixture A ------------- part Hydrated lime ---------------- 2 parts This combination contains 6.66 percent As 20s. Forty-nine applications of this insecticide were made under all conditions. The periods during which these applications were made were as follows: July 15 to September 30, 1921, and May 10 to June 21, 1922, or the equivalent of one growing season. Not the slightest trace of burning resulted from any of the applications and if there was any stunting of the plants it was so little in evidence that the professional grower would not admit it. The formula recommended for controlling the Mexican bean beetle is based on the proportion of materials in this mixture. This proportion is given in Table XL, page 69. Cal-Sulphur Cal-sulphur contains 6.66 percent As20 and is a stock mixture commercially made according to the formula recommended by this Station. It was tested in 38 applications made during the period of May 10 to June 25 and compared with the preceding mixture one which the formula is based. Control was equally as good and no traces of burning or other injury developed as a result of any of the applications. In addition to these tests this insecticide was very widely used in the infested area during 1922. Niagara Mixture A ----------- 2 parts Hydrated lime ---------------- 5 parts This combination contains 5.71 percent As 2 Os. Only 5 applications were made. A little benefit resulted from these applications but the infestation increased more rapidly than where stronger mixtures were used and the latter were substituted for this insecticide in order to hold the pest in check. Apparently this combination was too weak. Copper Calcium Arsenate (Dosch Mixture B-14) 20-10-70 This is another stock mixture. It contains 3.8 percent As 2Os. Fourteen applications of this insecticide weremade to different species and varieties of beans. They failed to control the insect except in one instance on butterbeans. Even this strength caused a brown color to develop around the margins of injured spots on leaves of butterbeans but no noticeable injury resulted. Py et ru m4IIll 1ixt1Ir4'- z14 I1It 1(4 14 (Ilc111 I I ( l hl furc1(1 Ih I':1111111141)5415beet5. ul 11c ~4 ) I fl4 I i(''4 ry 1\ sce I)' I)II o i e j r I'n l ure( I'- \ e. I ' 114114 F 1wi5I('I'\ Skit)41 4414. I44l' n r g :L u (I i' '-41111 1 wit1 I114 fun1 sll 44 411~.~l 1441 ~ sli ('4I 1 ust-N I~c ii 411 t)1c 1 e51-4 1144 (1(11ll 1(1'1) l Fie. '_.. 1141I 1d (iun in (1pc' ii ont111. Tis « (Iic thir t~c ( 1 FHs igi('l uIs(d. pI'oj)(lv Ili d )il splt on lthlc to 1he dus en o(1 ')1the( 8111i pread and an(1 (pfi (1h iV hI ,he und ler su ies of, the to liial hi~~~~~~~sc OI''h1v tile lls htII ai nI wiovl i-I ht x dus aiii 1116 es o[ 1~itlioti F)n;.h~l 3 ~ ~ j. ell hisesaiihs-1gl~li ~ ~~etcd ('85 regh o 11nd1 ple usedi is ltd oi v1114thisOh (- s ype ne)edediii dusta iush to ho hais\shih I 1( leansIouldi l'a(h4' ,heh slit tob put onl ltili julalid~ ilyfri\\ he 111o lie th satio[(nd ill l carry.111 hi shouldi order' hlI pl,ouX 11ed o kill thipe is ohdehill Irls. IW((~(i' dep h o h 1111ch 1s'- (t(8itil5(itl50111 96 cumulations of leaves on the margins of wooded areas and under single trees near locations where bean plantings suffered from attack of the insect. Colonies of beetles containing several hundred may be found. Fence rows and ditch banks should be cleaned up and the rubbish burned. Not only will these measures help in destroying the winter quarters, which is very important, but the numbers of beetles may be materially reduced. Early planting is advised, although no strong recommendations are given regarding the time of planting. It begins to appear as though late beans may suffer but little injury, when planted as late as a crop can be assured. Plant cowpeas and soy beans as in the past. Until more investigation sheds new light, no change in crops is advised. The greater the distance between beans and cowpeas, the safer it is for the peas. CONTROL METHODS The Mexican bean beetle can be controlled economically by dusting the foliage of beans. Several insecticides were used successfully. The one which is recommended has the following formula and contains 6.66 percent As20 5 : Percent Calcium arsenate (High grade) .16.66 Fine dusting sulphur------------16.66 Hydrated lime -----------------66.66 Green beans dusted with this insecticide are perfectly safe to be used as food, but washing is advised. It is recommended that applications of insecticides be made when the foliage is dry and when little wind is blowing. Four or five applications will usually be sufficient for protecting early planted bush varieties of snap or string beans. Those coming up about the middle of April should receive their first application in two or three weeks. The time of the first treatment for later plantings varies according to the infestation. Ordinarily it should begin soon after beetles are found, especially on beans planted after May. Applications to bush varieties should be made once each week, for if the infestation is once allowed to become abundant, a certain amount of injury will result. 97 Five applications beginning the first week in May provided good protection for early planted pole beans until the last of June. Control is more easily obtained on butterbeans than on snap beans. Treatment every ten days beginning the middle or last of May will be found amply sufficient to protect early planted butterbeans. The foliage of butterbeans, Phaseolus lunatus, is more susceptible than that of snap beans, P. vulgaris, to injury from the use of insecticides. Mature beans which have been well protected appear to be less attractive to the Mexican bean beetle and require very little in the way of treatment. When dusting pole beans, the dust cloud may become thick around the operator. Sometimes it is necessary to wear a handkerchief over the lower part of the face and tied behind the head. If cowpeas are being grown for seed and the vines become infested any of the insecticides recommended for use on beans will reduce the infestation and save the vines if applied in time. To facilitate the application of such treatments the cowpeas should be planted so that a skip occurs every fifth row, or if sown broadcast so that a space wide enough to walk is left between "beds" not over 12 feet in width. If cowpeas, to be fed as hay to livestock, are in danger from the beetle as a result of destroyed bean plantings, immediate cutting is advised. 98 BIBLIOGRAPHY (1) Mulsant, M. E. 1850. Species des Coleopteres Trimeres Securipalpes. Paris. (2) "Bland, H. J. 1864. Descriptions of New North American Coleoptera. In Proc. Ent. Soc. Phila., v. 3, p. 253-256. (3) Crotch, G. R. 1874. A revision of the Coleopterous Family Coccinellidae. London. (4) Riley, C. V. In 1883. Epilachna Corrupta as an Injurious Insect. General Notes, Amer. Nat., v. 17, p. 198-199. February. (5) Wielandy, J. F. 1889-90. Injurious Insects in New Mexico. In U. S. Dept. Agr., Insect Life, v. 2, p. 113-115. (6) 1891. The New Mexican Epilachna. In U. S. Dept. Agr., Insect Life, v. 3, p. 121-122. (7) Gillette, C. P. 1892. Observations upon Injurious Insects. Colo. Agr. Exp. Sta. Bul. 19. Gorham, H. S. (8) 1897. Biologia Centrali-Americana, Coleoptera, v. 7. (9) Griffin, H. H. 1897. Results of Experiments at the San Juan Substation. N. Mex. Agric. Exp. Sta. Bul. 21. (10) Gillette, C. P. 1899. Colorado's Worst Insect Pests and Their Remedies. Colo. Agr. Exp. Sta. Bul. 47. (11) Casey, T. L. In 1899. A Revision of the American Coccinellidae. Jour. N. Y. Ent. Soc., v. 7, p. 71-169. (12) Chittenden, F. H. 1899. Insects Injurious to Beans and Peas. In Yearbook U. S. Dept. Agr., 1898, p. 233-260. (13) Cockerell, T. D. A. 1900. Observations on Insects. N. Mex. Agr. Exp. Sta. Bul. 35. (14) Caudell, A. N. 1902. Notes on Colorado Insects. In Some Miscellaneous Results of the Work of the Division of Entomology. VI. U. S. Dept. Agr. Bur. Ent. Bul. 38. (15) Knaus, W. 1906. Coleoptera of the Sacramento Mountains of New Mexico. III. In Ent. News, v. 17, p. 329-333. (16) Fall, H. C., and Cockerell, T. D. A. 1907. The Coleoptera of New Mexico. In Trans. Amer. Ent. Soc., v. 33, p. 145-272. (17) Chittenden, F. H. 1907. Insects Injurious to Vegetables. New York. 99 (18) Sanderson, E. D. 1912. Insect Pests of Farm, Garden, and Orchard. New York. (19) Morrill, A. W. 1913. Entomological Pioneering in Arizona. In Jour. Econ. Ent., v. 6, p. 185-195. (20) Essig, E. O. 1915. Injurious and Beneficial Insects of California. (21) Merrill, D. E. 1917. The Bean Beetle. N. Mex. Agr. Exp. Sta. Bul. 106. (22) Orton, W. A., and Chittenden, F. H. 1917. Control of Diseases and Insect Enemies of the Home Vegetable Garden. U. S. D. A. Farmers Bul. 856. (23) Chittenden, F. H. 1919. The Bean Ladybird and Its Control. U. S. D. A. Farmers Bulletin 1074. (24) Chittenden, F. H., and Marsh, H. O. 1920. The Bean Ladybird. U. S. D. A. Bul. 843. (25) Montgomery. J. H. 1920. Notes from the Quarantine Department. Quar. Bul. State Plant Board of Fla. Vol. V., No. 1. p. 2. (26) Hinds, W. E. 1920. Mexican bean Beetle Situation, Jour. Eco. Ent. Vol. 13, No, 6, pp. 486-488. (27) 1921. The Mexican Bean Beetle, a New Pest in Alabama. Ala. Exp. Sta. Bul. 216. (28) Howard, Neale F. 1921. The Mexican Bean Beetle and Its Bearing on SFlorida Citrus Growing. Quart. Bul. State Plant Board of Fla. Vol. VI, No. 1, pp. 15-24. (29) Newell, Wilmon. Quart. Bul. State 1921. The Mexican Bean Beetle. Plant Board of Fla. Vol. V, No. 2, pp. 119-121. (30) List, Geo. M. 1921. The Mexican Bean Beetle. Col. Agr. Exp. Sta. Bul. 271. (31) Howard, Neale F. 1922. The Mexican Bean Beetle in the Southeastern United States. Jour. Eco. Ent. Vol. 15, No. 4, pp. 265-275. (32) Bentley. G. M. 1922. The Mexican Bean Beetle, a New and Serious Pest in Tennessee. Tenn. St. Bd. of Ent. Vol. XI, No. 2 Bul. 41. (33) Hinds, W. E 1923. Mexican Bean Beetle Control. Ala. Poly. Inst. Ext. Service, Cir. 61.